ADA-154319

NTIS
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U.S. DEPARTMENT OF COMMERCE
National Technical Information Service

			PAGE
Table of Contents			i
List of Figures			vi
List of Tables			viii
List of Terms			ix
Section	1.0	General Introduction	1
Section	2.0	Noise Metrics	7
	2.1	Introduction	9
	2.2	Single Event Maximum Sound Level Metrics	9
	2.2.1	A-Weighted Sound Level	9
	2.2.2	D-Weighted Sound Level	11
	2.2.3	Perceived Noise level (PNL)	11
	2.2.4	Tone Corrected Perceived Noise Level (PNLT)	12
	2.3	Single Event Energy Dose Metrics	12
	2.3.1	Effective Perceived Noise Level (EPNL)	12
	2.3.2	Sound Exposure Level (SEL)	12
	2.4	Cumulative Energy Average Metrics	12
	2.4.1	Equivalent Sound Level (Leq)	13
	2.4.2	Yearly Average Day-Night Sound Level (DNL	13
	2.4.3	Community Noise Equivalent level (CNEL)	13
	2.4.4	Noise Exposure Forecast (NEF)	13
	2.5	Cumulative Time Metrics	13
	2.5.1	24-Hour Above (TA)	13
	2.5.2	Day, Evening, Night (TA)	15
	2.6	DNL: The Standard Cumulative Average Energy Metric	15
	2.7	Evaluation of the DNL Metric for Heliport/ Helistop Noise Impact Assessment	15
	2.8	Summary of Noise Metric Policy	17
	2.9	Noise Metrics Applications	17
Section	3.0	Annoyance and Aircraft Noise	19
	3.1	Introduction	20
	3.2	Perception of Noise	20

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	3.3	Variables Affecting Response	20
	3.3.1	Emotional Variables	20
	3.3.2	Physical Variables	21
	3.4	Review of Recent Research	23
	3 5	Conclusion	26
Section	4.0	Different Sources/Different Human Response?	27
	4.1	Introduction	29
	4.2	Schultz - Kryter Debate	29
	4.3	Hall's Research and Analysis	31
	4.4	Conclusion	32
Section	5.0	Hearing and Hearing Loss	33
	5.1	Introduction	35
	5.2	The Hearing Mechanism	35
	5.3	Auditory Range	36
	5.4	Effects of Noise on Hearing	36
	5.4.1	TTS	36
	5.4.2	NIPTS	36
	5.5	Damage Risk Criteria	37
	5.6	Review of Studies	38
	5.6.1	Interior Aircraft Noise	38
	5.6.2	Community Hearing Loss	39
	5.7	Current Standards on Hearing Protection	39
	5.8	Protection of Hearing	41
	5.9	Conclusion	42
Section	6.0	Speech Interference	43
	6.1	Introduction	44
	6.2	Measures of Speech Intelligibility	44
	6.3	Assessing Speech Intelligibility	45

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	6.4	Speech Interference on the Ground	47
	6.5	Speech Interference in the Cockpit	49
Section	7.0	Sleep Interference	51
	7.1	Introduction	53
	7.2	Sleep Disturbance Response	53
	7.3	Recent Literature Review	53
	7.3.1	Arousal for Sleep	54
	7.3.2	Measuring Sleep Interference	54
	7.3.3	Adaptation and Habituation	55
	7.4	1977 Literature Review	55
	7 5	Summary	57
Section	8.0	Non-Auditory Effects of Noise	59
	8.1	Introduction	60
	8.2	Interpretation of Rulings	60
	8.3	Review of Studies	60
	8.4	Conclusion	61
Section	9.0	Effects of Noise on Wild and Domesticated Animals	63
	9.1	Introduction	65
	9.2	Wildlife	65
	9.2.1	Birds	65
	9.2.2	Fish	65
	9.3	Domesticated (Farm) Animals	66
	9.4	Laboratory Animals	66
	9.5	Conclusion	67
Section	10.0	Effects of Strong Low Frequency Acoustical Energy	69
	10.1	Introduction	70
	10.2	Structural Effects	70

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			PAGE
	14.3	Federal Interagency Criteria	95
	14.4	U.S. Air Force AICUZ Criteria	95
	14.5	HUD and VA Criteria	97
	14.6	Conclusion	97
Section	15.0	Effects of Aircraft Noise on Real Estate Values	99
	15.1	Introduction	100
	15.2	Research Considerations	l00
	15.3	Review of Research	l00
	15.4	Conclusion	101
Further Information			103

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		PAGE
1.1	Community Response to Aircraft Noise Near Major Airports	3
2.1	Frequency Spectrum	8
2.2	The Metric Family	l0
2.3	A and D weighting Curves	l0
2.4	Typical TA Data Presentation	14
3.1	Community Response to Aircraft Noise Near Major Airports	22
3.2	Community Response to Aircraft Noise --the Netherlands	22
3.3	Community Response to Aircraft Operations— London Heathrow	24
3.4	Comparison of Individual Annoyance and Community Reaction	25
3.5	Attitudes Toward Aircraft Noise	25
4.1	Summary of Annoyance Data from 11 Surveys	28
4.2	Schultz's Synthesis Curve	28
4.3	Hall's Comparison of Air, Road and Schult Synthesis Curve	30
5.1	Cross-Section of the Ear	34
5.2	Cross-Section of the Middle Ear	34
5.3	Damage Risk Criteria Curves	38
5.4	Attenuation by Earplugs	41
5.5	Attenuation by Earmuffs Combined with Earplugs	41
6.1	Calculated AI vs. Effective AI	44
6.2	Noise Criteria Curves	45
6.3	Permissible Distance Between a Speaker and Listeners of Voice and Ambient Level	47

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		PAGE
7.1	Sleep Stages	52
7.2	Sleep Disturbance by Noise	54
7.3	Composite of Laboratory Data for Sleep Interference	56
9.1	Dose Response of 11 Different Animal Species	64
10.1	Human Tolerance of Structural Vibration	72
10.2	Human Tolerance of Vibration Caused by Concorde	72
10.3	N-Wave Signature	73
10.4	Adverse Reactions to Sonic Booms	75
13.1	Typical Noise Contour	88
13.2	Applications of DNL 65 Contour	91
13.3	Applications of DNL 75 Contour	91

		PAGE
1.1	Comparative Noise Levels	2
2.1	Noise Metrics Applications	16
5.1	Permissible Noise Exposures	40
5.2	Limiting Values for Total Daily Noise Exposure	40
6.1	Speech Intelligibility Criteria	46
6.2	Recommended Noise Criteria for Offices and Workspaces	48
10.1	Interim Prediction of Effects of Ground Overpressure	74
12.1	Merits and Deficiencies of DNL	83
14.1	Comparison of ANSI and FAA Land Use Guidelines	95
14.2	FAA Land Use Compatibility Guidelines	96
14.3	U.S. Air Force Land Use Objectives Matrix	98
15.1	Damage Estimates for Property Values	101

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AI	Articulation Index
AICUZ	Air Installation Compatible Use Zones
AIR	Aerospace Information Report
ALM	A-Weighted Maximum Sound Level
ANSI	American National Standards Institute
ARP	Aerospace Recommended Practice
CHABA	Committee on Hearing, Bioacoustics and Biomechanics
CNEL	Community Noise Equivalent Level
CNR	Composite Noise Rating
dB	Decibel
DNL	Day-Night Average Noise Level
DOT	Department of Transportation
DRC	Damage Risk Criteria
EPA	Environmental Protection Agency
EPNL	Effective Perceived Noise level
HUD	Housing and Urban Development
Hz	Hertz
ICAO	International Civil Aviation 0rganization
IEC	International Electrotechnical Commission
ISO	International Standards 0rganization
Ldn	Day-Night Average Sound Level
Leq	Equivalent Sound Level
Lx	An Airport Cumulative Metric Derived from dBA

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Section 1.0 General Introduction

Aviation noise significantly affects several million people in the United States. In a great number of instances, aircraft noise simply merges into the urban din, a cacophony of buses, trucks, motorcycles, automobiles and construction noise. However, in locations closer to airports and aircraft flight tracks, aircraft noise becomes more of a concern. The Federal Aviation Administration (FAA) presents this report in an effort to enhance public understanding of the impact of noise on people and to answer many questions that typically arise. Information on aircraft noise indices, human response to noise, and criteria for land use controls is included. Additionally, information on hearing damage is presented, along with occupational health standards for noise exposure.

This document has been developed after reviewing the rather extensive literature in each topical area, including many original research papers, and also by taking advantage of literature searches and reviews carried out under FAA and other Federal funding over the past two decades. Efforts have been made to present the critical findings and conclusions of pertinent research, providing, when possible, a "bottom line" conclusion, criterion, or perspective to the reader concerned with aviation noise.

How to Read This Document

1. If you want only a general, non-technical presentation of the fundamental issues and concerns with aircraft noise, read this introduction and the one-page summaries at the beginning of each section.

2. If you are an engineer, planner, social scientist or an individual conducting an environmental impact, assessment, consider reading each section of interest in its entirety.

3. If you wish to do an in-depth study, assessment or analysis, delve into the text and the references listed. For more information, consider contacting the staff of the FAA 0ffice of Environment and Energy, Noise Abatement Division,, in Washington, D.C. 20591.

What is Sound?

Sound is a complex vibration transmitted through the air which, upon reaching our ears, may be perceived as beautiful, desirable, or unwanted. It is this unwanted sound which people normally refer to as noise.

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Typical Decibel (dBA) Values Encountered in Daily Life and Industry*

Rustling leaves	20 dBA
Room in a quiet dwelling at midnight	32
Soft whispers at 5 feet	34
Men's clothing department of large store	53
Window air conditioner	55
Conversational speech	60
Household department of large store	62
Busy restaurant	65
Typing pool (9 typewriters in use)	65
Vacuum cleaner in private residence (at 10 feet)	69
Ringing alarm clock (at 2 feet)	80
Loudly reproduced orchestral music in large room	82

Beginning of hearing damage if prolonged exposure over 85 dBA

Printing press plant	86
Heavy city traffic	92
Heavy diesel-propelled vehicle (about 25 feet away)	92
Air grinder	95
Cut-off saw	97
Home lawn mower	98
Turbine condenser	98
150 cubic foot air compressor	100
Banging of steel plate	104
Air hammer	107
Jet airliner (500 feet overhead)	115

* When distances are not specified, sound levels are the value at the typical location of the machine operator.

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How Does Sound Get Around?

Sound moves outward from its point of origin in waves just as ripples move outward from the point at which a pebble enters a pond.

Sound, just as the ripple in the pond, requires a medium in which to travel; this medium is usually air.

What is a Decibel?

The decibel (dB) is a shorthand way to express the amplitude of sound (the relative height of those ripples in the pond). Because the "ripples" of sound typically experienced may vary in height from 1 to 100,000 "units", it becomes rather cumbersome to maintain an intuitive feeling for what different values represent. The decibel allows people to understand sound strength using numbers ranging between 20 and 120, a more familiar and manageable set of values. Table 1.1 provides a listing Of some typical sounds and their respective sound levels (expressed in decibels) at given distances.

The decibel also relates well to the way in which people perceive sound. A 10 dB increase in a sound seems twice as loud to the listener, while a 10 dB decrease seems only half as loud. In general, changes in sound level of 3 or 4 dB are barely perceptible.

What is Frequency or Pitch?

Some of the ripples in the pond may be very short; these are analogous to high pitched sounds such as the voice of a soprano. Other wavelets might be very broad; these waves are analogous to a bass or baritone voice. Most sounds we hear are composed of a mixture of these different length sound waves, giving complexity, richness and character to our experience of sound.

What is the Most Important Effect of Aviation Noise?

Annoyance is the most prevalent effect of aircraft noise. It is important to note that while the overall, or average, community attitude about a noise level is usually what is reported, some individuals will be much more and others much less upset or annoyed with the sound in question. Figure 1.1 shows this typical response pattern. This variation in response is what makes the science of measuring "community response" a rather complicated matter.

What are Other Principal Effects of Aircraft Noise?

1. speech interference

2. sleep interference

3. hearing damage risk

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_ Ref 1

While hearing damage is not a common result of aircraft noise exposure, speech and sleep interferences are major concerns of neighbors close to airports.

What are Some Less Frequently Identified Effects of Noise on Humans?

1. physiological (cardiovascular and circulatory) problems

2. psychological problems (stemming from intense annoyance)

3. social behavioral problems

At the present time there is no conclusive evidence to link these effects with aircraft noise. As discussed in the text, these topical areas are often rife with conflicting research results and are very controversial. The summary of the non-auditory effects section (Section 8.0) provides current guidance for interpreting these reported effects.

What Other Areas May be Affected by Aircraft Noise?

1. real estate values

2. land use

3. wildlife

4. farm animals

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Years of experience in airport planning and development have resulted in guidelines which match uses of land -- like hospitals or concert halls -- with normally compatible noise levels; these guidelines are published in an FAA regulation called Federal Aviation Regulation (FAR) PART 150. Implementation of an FAR150 study will assist airport operators and neighbors in minimizing the extent of non-compatible land uses.

While the reactions of animals to noise have been studied, it is another research area plagued with widely varying results. In all but extreme cases (such as in pristine wilderness or in the case of excessive noise levels) wildlife and domesticated animals rarely display any reactions to aviation noise.

How Do You Measure Aircraft Noise?

sound is often measured using a sound level meter with a filter which simulates the human hearing response. This filter and the human ear give greater emphasis to sounds in the speech-important frequency bands and less emphasis to the lower and higher frequencies. This differential response in the human ear may have developed over the course of human evolution as a way to filter the sounds of wind and water which might interfere with survival-related communications such as "Here comes a Tyrannosaurus Rex--run for it!" In any event, this filter is called the A-weighting filter, and the sound measured with this filter is called the A-level (AL).

Now I Know What AL is, but I Am Confused About "Energy Dose." What Exactly is the Sound Exposure Level (SEL)?

When our sound level meter is measuring the AL, think of the sound falling on the microphone like rain or snow. The maximum rate of rainfall is the maximum AL. Now consider the sound level meter as a bucket or pail. After the "noise event" has passed (aircraft flyover or truck passby) the rain or snow collected in the bucket (having passed through the microphone) is the noise dose or Sound Exposure Level (SEL). Essentially, loud noise events create a large bucket (dose) of sound energy, while quieter events create smaller buckets.

Now What Do I Do With "Buckets" of Noise (the Leq and DNL)?

The buckets are typically collected over a 24-hour time period and are poured into a large container. The total volume collected during the 24-hour time period is averaged to formulate a value called the "Equivalent sound Level", or Leq. When the buckets collected during the nighttime hours are multiplied by 10 (because of greater potential for disturbing people) and then the volume averaged, we formulate a value called the "Average Day Night sound Level" or DNL. The Leq and DNL are values one often encounters in looking at the overall noise exposure from an airport operation.

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1. Richards, E. S, and J. B. Ollerhead. Noise Burden Factor-
-New Way of Rating Airport Noise. Sound and Vibration,
V.7, No, 12, December 1973.

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Section 2.0 NOISE METRICS

INTRODUCTION

This section describes the noise metrics utilized in conducting analyses of aircraft noise. While dozens of additional metrics exist, this section focuses on the officially designated family of indices. A working knowledge of these measures is extremely valuable in understanding the remainder of this report.

AVIATION APPLICATIONS/ISSUES

1. Correlation between human response and various measures of sound.

2. Selection of the best metrics for specific applications.

3. Selection of weighting factors for sound occurring at various times of day.

4. Selection of metrics which are accurate, relatively easy to measure, compute and understand.

GUIDANCE/POLICY/EXPERIENCE

1. The fundamental sound level metric designated as the A-Weighted Sound Level, or AL. This metric has often appeared in the literature as dBA. It is designated for measuring noise at an airport and surrounding areas by Part 150.

2. Single event dose or energy metric designated as the Sound Exposure Level or SEL.

3. Airport yearly average noise exposure measure designated as the Yearly Average Day Night Level or DNL. The DNL has often appeared in the literature as Ldn.. Required by Part 150 to measure the exposure of individuals to noise resulting from the operation of an airport.

4. Effective Perceived Noise Level or EPNL designated as the certification metric for large transport turbojet aircraft and helicopters.

5. Time functions of ALm (such as Time Above, TA and L-Values, L-10) identified as supplementary metrics for use in environmental impact analyses.

6. Octave and one-third octave spectra identified as important in specific applications such as sound proofing and speech interference studies.

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(2) Single Event Energy Dose

(3) Cumulative Energy Average Metrics

(4) Cumulative Time Metrics

The paragraphs below describe and differentiate these four generic classes of acoustical metrics. An understanding of these four classes essential for an individual undertaking a comprehensive assessment of noise effects. (For mathematical formulations of each of the noise metrics, the reader is referred to The Handbook of Noise Ratings (Ref. 1).

2.2 SINGLE EVENT MAXIMUM SOUND LEVEL METRICS

The following noise metrics are generally related, each representing a maximum sound level. The applications of these metrics are diagrammed in Figure 2.2.

2.2.1 A-Weighted Sound Level: ALm (Historically dBA), Expressed in dB. The A-weighted Sound Level is the single event maximum sound level metric. A-weighted sound pressure level is sound pressure level which has been filtered or weighted to reduce the influence of the low and high frequency extremes. Because unweighted sound pressure level does not correlate well with human assessment of the loudness of sounds, various weighting networks are added to sound level meters to attenuate low and high frequency noise in accordance with accepted equal loudness contours. One of these weighting networks is designated "A" (shown in Figure 2.3).

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It was originally employed for sounds less than 55 dB in level; now A-level is used for all levels of sound because it has been found to correlate well with people's subjective judgment of the loudness of sounds. Its simplicity and superiority over unweighted SPL in predicting people's responses to noise have contributed to its wide acceptance. The ALM is currently used for noise certification of small propeller-driven aircraft; also, in FAA Advisory Circular 36-3C it is used as the basis for airport access restrictions which discriminate solely on the basis of noise level.

2.2.2 D-Weighted Sound Level: DLm (Historicall dB(D)), Expressed in dB. D-weighted sound pressure level or D-level is sound pressure level which has been frequency-filtered to reduce the effect of the low frequency noise and to recognize the annoyance at higher frequencies. D-level is measured in decibels with a standard sound level meter with contains a "D" weighting network with the response curve shown in Figure 2.3. D-level was developed as a simple approximation of perceived noise level (PNL) for use in assess aircraft noise. PNL, addressed in the next paragraph, can be estimated from the D-level by this equation: PNL = dB(D) + 7.

2.2.3 Perceived Noise Level (PNL), Expressed in dB. Perceived Noise Level (PNL) is a rating of the noisiness that has been used almost exclusively in aircraft noise assessment. PNL is computed from sound pressure levels measured in octave or one-third octave frequency bands. This rating is most accurate in estimating the perceived noisiness of broadband sounds of similar time duration which do not contain strong discrete frequency components. Currently it is used by the FAA and foreign governmental agencies in the noise certification process for all turbojet -- powered aircraft and large propeller-driven transports. The perceived noise level is expressed in decibels. These units translate the subjective linearly additive noisiness scale to a logarithmic dB-type

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acoustical energy associated with the fluctuating sound (during the prescribed time period) is equal to the total acoustical energy associated with a steady sound level of Leq for the same period of time. The purpose of Leq is to provide a single number measure of noise averaged over a specified time period.

2.4.2 Day-Night Sound Level (DNL), Expressed in dB. Day-Night Sound Level (DNL) was developed as a single number measure of community noise exposure. It is often referred to as Ldn in the literature. DNL was introduced as a simple method for predicting the effects on a population of the average long term exposure to environmental noise. It is an enhancement of the Equivalent Sound Level (Leq) because a correction for nighttime noise intrusions was added. A 10 dB correction is applied to nighttime (10 p.m. to 7 a.m.) sound levels to account for increased annoyance due to noise during the night hours. DNL uses the same energy equivalent concept as Leq. The specified time integration period is 24 hours. As in the case of Leq, there is no stipulation of a minimum noise sampling threshold. The DNL can be derived directly from the A-weighted sound level or the sound exposure level, as shown in Figure 2.2. For assessing long term noise exposure, the yearly average DNL (DNL y-avg) is the specified metric in the FAA FAR Part 150 noise compatibility planning process. In the remainder of this document, the term DNL will be used (in lieu of DNL y-avg), yearly average being implied.

2.4.3 Community Noise Equivalent Level (CNEL), in dB. CNEL, like DNL, incorporates the energy average A-weighted sound level integrated over a 24-hour period Weightings are applied for the noise levels occurring during the evening (7 p.m. - 10 p.m.) and nighttime (10 p.m. - 7 a.m.). CNEL differs from DNL in the addition of the evening weighting step function of 3 dB which is intended to account for activity interference and annoyance during that time period. It was originally used by the state of California, but it is being phased out.

2.4.4 Noise Exposure Forecast (NEF), in dB. Noise Exposure Forecast performs the same role as DNL or CNEL but is developed using EPNL as the intermediate single event dose metric. The NEF metric incorporates a weighting factor which effectively imposes a 12.2 dB penalty on sound occurring between 10 p.m. and 7 a.m. This corresponds to a nighttime event multiplier of 16.7. NEF correlates extremely well with DNL and the equivalency DNL = NEF + 35 is often used.

2.5 CUMULATIVE TIME METRICS

2.5.1 24-Hour Time Above (TA), Expressed in Minutes. The 24-hour TA metric provides the duration in minutes for which aircraft related noise exceeded specified A-weighted sound levels. An example of a TA contour is shown in Figure 2.4. TA is one of the criteria specified in HUD Circular 1390.2 for determining eligibility for HUD construction funding (Ref. 3). TA'S inverse, the L-value (e.g., L 10) is used (along with Leq) as the FHWA criteria for planning and design of Federal-aid highways. Further, TA can be related directly to some "threshold activated" physiological or annoyance effects.

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2.5.2 Day, Evening, Night (TA), Expressed in Minutes. The Day-TA metrics provide the duration in minutes for which aircraft related noise exceeded specified A-weighted sound levels during the period 7:00 a.m. to 7:00 p.m. The Evening TA metrics provide the duration in minutes for which aircraft related noise exceeded A-weighted sound levels during the period from 7:00 p.m. to 10:00 p.m. The Night TA metrics provide the duration in minutes for which aircraft related noise exceeded A-weighted sound levels during the period from 10:00 p.m. to 7:00 a.m.

2.6 DNL: THE STANDARD CUMULATIVE AVERAGE ENERGY METRIC

The FAA selected DNL as the cumulative average energy metric to be used in airport noise exposure studies. While a dialogue continues within research circles concerning weighting functions, the DNL has emerged as a sound and workable tool for use in land use planning and in relating aircraft noise to community reaction. The substantiating basis for the DNL can perhaps best be summarized as follows:

1) Pragmatically speaking, it works. Engineers and planners have acquired over 30 years working experience with a nominal 10 dB nighttime weighting function. This experience has been successful, contributing to wise zoning and planning decisions.

2) The nominal 10 dB decrease in ambient noise levels in many residential areas at nighttime provides a sensible basis for the weighting factor.

2.7 EVALUATION OF THE DNL METRIC FOR HELIPORT/HELISTOP NOISE IMPACT ASSESSMENT

With the increase in helicopter operations in and around urban areas, the FAA has sought to include helicopters in the environmental planning process. In this context, the question has arisen of whether or not the average cumulative energy metric DNL, which is used in the analysis of noise from conventional aircraft, would also be appropriate for analysis of helicopter noise. Most commercial airports have hundreds of operations a day, while heliports generally handle fewer than thirty. The metric used to analyze helicopter noise would have to be sensitive enough to accurately reflect community response at comparatively low levels of noise exposure (lower cumulative levels because of fewer flights).

In order to investigate whether or not DNL would be appropriate, the FAA supported a field test program to examine subjective response to helicopter operations. The actual study was conducted by NASA Langley Research Center and is summarized below (Ref. 4). In the study, researchers examined the reaction of community residents to low numbers of helicopter noise events. Residents of the selected community were interviewed twenty-three times about their general noise annoyance on particular days. Unknown to them, on those days helicopter flights had been controlled for the test purpose; the number of flights per day varied from 0 to 32. The exposure varied randomly through each of the

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METRIC	DESCRIPTION
One-third Octave Sound Pressure Levels	The one-third octave band sound pressure levels are the starting point for all other metrics; useful in implementation of soundproofing
PNL	Sound Level from which EPNL was developed
PNLT	Sound Level from which EPNL was developed
EPNL	A maximum sound level single event cumulative metric developed from the PNLT and PNL sound level. Used in FAR Part 36, Appendix C Certification, Advisory Circular 36-lB and Advisory Circular 36-2A.
NEF	An Airport cumulative metric no longer in use in the U.S. but often used in older studies; replaced by DNL (the FAA approved metric)
Alm	A sound level metric applied as follows: Airport Noise Analysis 1050.lC Analysis FAR Part 36 Appendix F Certification Specific eligibility for Soundproofing Implementation of Soundproofing Noise Monitoring Systems FAA Advisory Circular
TA	An airport cumulative metric derived from dB(A) and applied as follows: Airport Noise Analysis l050.lD Analysis Noise Monitoring Systems
Lx	An airport Cumulative metric derived from dB(A) and applied as follows: Airport Noise Analysis l050.lD Analysis Noise Monitoring Systems
SEL	A maximum sound level, single event cumulative metric derived from dB(A) and applied as follows: Airport Noise Analysis Noise Monitoring Systems
Leq	An airport cumulative metric derived from SEL; no application in aviation
DNL	An airport cumulative metric derived from SEL with the following applications: Airport Noise Contours Airport Noise Analysis FAR l050.lD Analysis General Eligibility for Soundproofing Noise Monitoring Systems
CNEL	An airport cumulative metric derived from SEL used only by the state of California; CNEL will be phased out in the next few years.

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1. Pearson, Karl. Handbook of Noise Ratings. Bolt, Beranek and Newman, Inc. NASA CR-2376, April 1974.

2. Hassall, J.R. and K. Zaveri. Acoustic Noise Measurements. Bruel & Kjaer, January 1979.

3. Housing and Urban Development Circular 1390.2.

4. Fields, James M. and Clemans A. Powell. Community Survey of Helicopter Noise Annoyance Conducted Under Controlled Noise Exposure Conditions. Unpublished Report, December 1984.

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Section 3.0 ANNOYANCE AND AIRCRAFT NOISE

INTRODUCTION

The typical response of humans to aircraft noise is annoyance. Annoyance response is remarkably complex and, considered on an individual basis, displays wide variability for any given noise level. Fortunately, when one considers average annoyance reactions within a community, one can develop aggregate annoyance response/noise level relationships. This section introduces the reader to the factors which influence individual annoyance response. Also included are examples of research findings which display aggregate community annoyance responses.

AVIATION APPLICATION/ISSUES

Annoyance is the number one consequence of excessive aircraft noise. The continued growth of the aviation industry and expansion of airport capacity is in part dependent on how well noise compatibility planning is handled.

GUIDANCE/POLICY/EXPERIENCE

It is the charter of the FAA to assure safety and promote civil aviation. Promoting civil aviation means, among other things, addressing the problems of aircraft noise annoyance. The FAA, working with other members of the community, has taken a series of steps designed to bring about greater compatibility between aircraft noise levels and affected individuals. Actions include:

1. Source noise certification regulations
2. FAR Part 150 Airport Noise Exposure / Land Use Compatibility Planning Process
3. Research into the mechanism of annoyance to aircraft noise
4. Advisory publications designed to mitigate aircraft noise impact on noise sensitive areas.

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alienated or of being ignored and abused is the root of many human annoyance reactions. If people feel that those creating the noise care about their welfare and are doing what they can to mitigate the noise, they are usually more tolerant of the noise and are willing and able to accommodate higher noise levels.

B. Judgment of the Importance and Value of the Activity which is Producing the Noise. If the noise is produced by an activity which people feel is vital, they are not as bothered by it as they would be if the noise-producing activity was considered superfluous.

C. Activity at the Time an Individual Hears a Noise. An individual's sleep,, rest and relaxation have been found to be more easily disrupted by noise than his communication and entertainment activities.

D. Attitudes about Environment. The existence of undesirable features in a person's residential environment will influence the way in which he reacts to a particular intrusion.

E. General Sensitivity to Noise. People vary in their ability to hear sound, their physiological predisposition to noise and their emotional experience of annoyance to a given noise.

F. Belief about the Effect of Noise on Health. The extent to which people believe that exposure to aircraft noise will damage their health affects their response to aviation noise.

G. Feeling of Fear Associated with the Noise. For instance, the extent to which an individual fears physical harm from the source of the noise will affect his attitude toward the noise.

3.3.2 Physical Variables. A number of physical factors have also been identified by researchers as influencing the way in which an individual may react to a noise. These factors include:

A. Type of Neighborhood. Instances of annoyance, disturbance and complaint associated with a particular noise exposure will be greatest in rural areas, followed by suburban and urban residential areas, and then commercial and industrial areas in decreasing order. The type of neighborhood may actually be associated with one's expectations regarding noise there. People expect rural neighborhoods to be quieter than cities. Consequently, a given noise exposure may produce greater negative reaction in a rural area.

B. Time of Day. A number of studies has suggested that noise intrusions are considered more annoying in the early evening and at night than during the day.

C. Season. Noise is considered more disturbing in the summer than in the winter. This is understandable since, during the summer, windows are likely to be open and recreational activities take place out of doors.

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D. Predictability of the Noise. Research has revealed that individuals exposed to unpredictable noise have a lower noise tolerance than those exposed to predictable noise.

E. Control over the Noise Source. A person who has no control over the noise source will be more annoyed than one who is able to exercise some control.

F. Length of Time an Individual Is Exposed to a Noise. There is little evidence supporting the argument that annoyance resulting from noise will decrease with continued exposure; rather, under some circumstances, annoyance may increase the longer one is exposed.

3.4 REVIEW OF RECENT RESEARCH

The inherent variability in the way individuals react to noise makes it impossible to predict accurately how any one individual will respond to a given noise. However, when one considers the community as a whole, trends emerge which relate noise to annoyance. In this way it is possible to correlate DNL with community annoyance. This measure will represent the average annoyance response for the community.

In any community there will be a given percentage of the population highly annoyed, a given percentage mildly annoyed and others who will not be annoyed at all. The changing percentage of population within a given response category is the best indicator of noise annoyance impact.

Various studies have focused on the relationship between annoyance and noise exposure, one researcher, in analyzing the results of numerous social surveys conducted at major airports in several countries, derived the curves shown in Figure 3.1 relating degree of annoyance and percent of population affected with noise exposure expressed in DNL (Ref. 1). A survey conducted in the Netherlands investigated the relationship between the DNL and the percentage of those questioned who suffered feelings of fear, disruption of conversation, sleep or work activities (Ref. 2). Figure 3.2 reflects these findings.

In 1960 the "Wilson Committee" was appointed by the British Government to investigate the nature, sources and effects of the problem of noise (Ref. 3). The final report, published in 1963, included results of extensive examination of community response to aircraft operations at London Heathrow Airport. Figure 3.3, adapted from that report, shows the relationship between DNL and the percent of the population disturbed in various activities including sleep, relaxation, conversation and television viewing. Disturbance response categories for startle and house vibration are also included.

The EPA publication "Information on Levels of Environmental Noise Requisite to Protect Health and Welfare with an Adequate Margin of Safety" provides a relationship between the percent of population highly annoyed and the Day-Night Sound Level (DNL) (Ref. 4). These data are shown in Figure 3.4, along with the relationship between annoyance, complaints and community reaction.

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3.5 CONCLUSION

This section has presented a series of relationships useful in interpreting average community response to aircraft noise. These data should provide the reader with the necessary perspective to begin understanding the human reactions to various levels of cumulative noise exposure (DNL).

1. Richards, E. J, and J. B. 0llerhead. Noise Burden Factor - New Way of Rating Airport Noise. Sound and Vibration, V. 7, No, 12, December 1973.

2. Kryter, Karl D. The Effects of Noise on Man. New York, Academic Press, 1970.

3. Great Britain Committee on the Problem of Noise. Noise, Final Report. Presented to Parliament by the Lord Minister for Science by Command of Her Majesty. London, H. M. Stationery Office, July 1963.

4. U.S. Environmental Protection Agency, Office of Noise Abatement and Control, Washington, D.C. Information on Levels of Environmental Noise Requisite to Protect Public Health and Welfare with an Adequate Margin of Safety. March 1974.

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Section 4.0 DIFFERENT SOURCES/DIFFERENT HUMAN RESPONSE?

INTRODUCTION

This section addresses a fundamental question raised from time to time in connection with aviation noise related law suits, environmental impact assessments, and research studies. It has been suggested that aircraft noise levels should be treated as more annoying to people than the same sound levels generated by other sources. A review of the research shows that very strong positions have been taken both supporting and opposing the theory. The most recent papers appearing in the scientific journals concede that a differential in response may exist but it can not be shown to be statistically significant.

AVIATION APPLICATIONS/ISSUES

Should aircraft noise be considered as comparable to noise from other sources in the land use planning and environmental assessment process?

GUIDANCE/POLICY/EXPERIENCE

In the general application of noise exposure/land use criteria, aircraft noise should be considered in the same manner as noise from other sources.

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4.1 INTRODUCTION

In assessing comparative contributions to the overall annoyance with noise experienced by an individual, the issue of whether or not aircraft noise should be compared with other ambient sources continues to arise. The issue is an important one in terms of establishing acceptable cumulative noise exposure levels for various land use categories. This section reviews current literature on this controversial topic.

4.2 SCHULTZ - KRYTER DEBATE

In 1978, Theodore Schultz published an article synthesizing results from many social surveys on noise annoyance. In this article he stated that it is possible to compare aircraft and other transportation noise equally, and to find and use a median annoyance response curve for them (Ref. 1). In order to compare these various results, Schultz developed some theories and formulas with which he determined which parts of each survey would fall into the "highly annoyed" category. He also figured the DNL indices for these surveys and plotted them (see Figure 4.1). Figure 4.2 reproduces Schultz's "synthesis curve", the median of all the noise surveys.

Karl Kryter, responding in 1982 to Schultz's article, proposed a different relationship (Ref. 2).. While Schultz only considered people who were highly annoyed, Kryter stated that all individuals annoyed should be considered in these comparisons. He also developed the DNL values for each study differently, so his values varied significantly from those of Schultz. Kryter also attempted to explain the poor correlation between noise exposure and annoyance in individuals by explaining that, while it is assumed that noise exposure is homogeneous over a given neighborhood, an individual's particular dose of noise may vary quite a bit.

Kryter cited Grandjean (Ref. 3), another researcher who found that aircraft noise is significantly more disturbing than other noise. This Swiss study stated that it took a DNL of 10 to 15 dB higher for road traffic noise to cause equal disturbance as aircraft. Kryter then explained his concept of the "effective exposure" of noise, rather than the exposure that may actually be measured or reported. Kryter suggests that because aircraft noise falls over a structure, like a house, equally, as opposed to passing through interfering structures as traffic noise would do (as in moving from the front to the back of a house), the "effective noise exposure" would be greater than that of traffic noise. Kryter further submits that, for a house facing the road, residents in the back yard would experience diminished noise from those in the front yard; however, they would all experience equal aircraft noise. Likewise, each room in the house would experience nearly identical exposure to aircraft noise (Kryter evidently only considered single - level homes). Kryter found a front to back of house difference of 17 - 21 dB for road traffic and only 0.3 dB for aircraft noise. Thus, Kryter suggests that aircraft noise must be considered separately from other transportation noise.

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For the same noise level, a greater percentage of
people are highly annoyed by aircraft noise. The
difference in annoyance at the two sources is not
constant but instead increases as Ldn increases. The
difference in annoyance is equivalent to about 8 dB at
Ldn of 55 dB increasing to about 15 dB at Ldn of 65 dB.

Hall puts forth some possible explanations of these variations. For example, the sporadic time pattern of aircraft noise differs from the relatively steady noise of road traffic. Thus, maximum levels for aircraft noise will be higher. Hall suggests that until further work can be done, "Ldn is a reasonable predictor of response to any particular source, but there are differences in response to different sources at the same Ldn value." Hall concluded that the best thing to do, then, would be to use separate functions to estimate community response to different types of noise.

In a later article (published in December 1984), Hall further addressed this complex issue, substantially altering his previous conclusions (Ref. 5). He references about a dozen papers published on this subject over the last five years. Hall suggests that intrinsic differences may exist but can not be substantiated as statistically significant. His summary statements are excerpted below:

The overwhelming conclusion from the recent literature is that different studies have led to different dose-response functions. This has happened for different sources, for different types of one source, and even for different studies at the same location (e.g., Heathrow). There is some consistency of evidence that the annoyance response function for rail noise is lower than for road or aircraft noise. (Rohrmann reaches the same conclusion in his review of relevant literature.) There is also some indication, but with fewer studies pertaining to it, that the aircraft annoyance function is higher than that for road traffic. However, the evidence is not strong enough to totally reject the hypothesis that all of this is just random variation about the "average" response.

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Lastly, an "average" dose-response function appears to be useful in two contexts, both defined by limited information. The first is the general situation we are now in, in which it appears that different dose-response functions are warranted, but we cannot specify precisely the conditions calling for each. Although we suspect the variance in results is not simply random, it almost behaves as if it were, in which case the "average" function represents our best current estimate. The second situation will arise in the future, when we may be able to specify clearly the conditions calling for separate dose-response functions. Even then, there will undoubtedly be conditions which we cannot categorize, in which case again the "average" response function would be. the best one to use.

4.4 CONCLUSION

For matters of policy, there does not exist at this time enough evidence to support the requirement of a differential for comparing aircraft noise with noise from other sources. All transportation and other ambient noise sources therefore can be treated as comparable when considering aviation noise impact.

1. Schultz, Theodore. Synthesis of Social Surveys on Noise Annoyance. J. Acoust. Soc. Am. 64, 1978.

2. Kryter, Karl D. Community Annoyance from Aircraft and Ground Vehicle Noise. J. Acoust. Soc. Am. 72 (4), October 1982.

3. Grandjean, P. Graf, A. Lauber, H.P. Meier, and R. Huller. Survey on the Effects of Aircraft Noise in Switzerland. Inter-Noise 76, Washington, D.C., April 1976.

4. Hall, Fred L., Susan E. Bernie, Martin Taylor, and John E. Palmer. Direct Comparison of Community Response to Road Traffic Noise and to Aircraft Noise. J. Acoust, Soc. Am. 70 (6), December 1981.

5. Hall, Fred L. Community Response to Noise: Is All Noise the Same? J. Acoust. Soc. Am. 76 (4), October 1984.

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INTRODUCTION

This section describes the human hearing mechanism and the processes of temporary and permanent hearing loss. The results of research are presented and the potential for hearing loss in aviation noise environments evaluated. OSHA hearing protection criteria are also addressed.

AVIATION APPLICATIONS/ISSUES

1. Permanent or temporary hearing loss.
a. cockpit crew
b. flight attendants
c. passengers
d. persons in communities exposed to aircraft
overflight

2. Temporary hearing loss for the same categories of individuals listed above.

GUIDANCE/POLICY/EXPERIENCE

1. FAA-sponsored research results show that permanent hearing loss is not a likelihood for a) cockpit crew, b) flight attendants, c) passengers, d) people exposed to overflights.

2. Temporary hearing loss (up to several hours recovery time) may occur in commercial aviation noise environments. These temporary sensitivity shifts are not unusual in the industrial setting and do not exceed OSHA criteria.

3. Persons on the ground exposed to aircraft overflights would typically not experience any temporary hearing loss due to the relatively short duration of the noise exposure.

4. A greater degree of temporary and possible permanent hearing loss can result in the case of long exposure times in certain small propeller driven aircraft.

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5.1 INTRODUCTION

It is well established that continuous exposure to high levels of noise will damage human hearing. This section begins with a description of the hearing mechanism, followed by discussion of the effects of noise on hearing, along with criteria for hearing protection established by the military, the FAA and OSHA. Finally, methods for protection of hearing are discussed.

5.2 THE HEARING MECHANISM

The ear is an external sense organ designed to receive and respond to air-borne acoustic vibratory energy. Figure 5.1 provides a schematic cross section showing the outer, middle and inner ears. The external ear, made up of the auricle (the outer portion of the ear) and the ear canal, transmits sounds to the eardrum. The eardrum, which is a very thin membrane that moves very slightly in response to sound pressure levels, separates the ear canal from the middle ear.

The middle ear is an air-filled cavity that lies between the outer and the inner ear (see Figure 5.2). It acts as a mechanical amplifier of the air pressure vibrations from the eardrum and through a series of bones called the ossicles. Air pressure vibrations displace the eardrum, which then displaces the ossicles, a link of three small bones which reach across the middle ear cavity to the delicate, fluid-filled membranes of the inner ear. The ossicles, made up of the malleus, the incus and the stapes, rest against the opening to the inner ear, the oval window; when the ossicles are displaced, the stapes pushes through the oval window, displacing the fluid in the inner ear.

The middle ear allows pressure variations in air to be transmitted into pressure variations in fluid with very little loss of energy. This is due in part to the relative size difference between the eardrum and the oval window (the eardrum has an area 20 times that of the oval window). Thus, the force exerted on the inner ear fluid by the stapes is about the same as the force exerted on the eardrum by the sound wave in the air, but the resulting pressure is much greater -- as much as a ratio of 22 to 1.

The inner ear contains the final section of the organ of hearing, the cochlea, which rests, coiled like a snail, against the oval window. As the stapes forces the oval window in and out, the fluid of the cochlea is also moved. About thirty thousand hair cells (called cilia) located in the cochlea react to the fluid motions, translating them to nerve impulses (and converting them from mechanical to electrical energy), then transmitting the impulses to the brain for interpretation.

Acoustical energy may also be conducted to the inner ear through vibration of bone. An example is the sound of one's own voice. Bone-conducted vibrations set up similar patterns of vibration of the cochlear partition as does air-conducted sound.

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the effects of noise on the crew and passengers inside an aircraft or on the effects of noise on individuals regularly exposed to aviation noise, such as people who reside around airports.

5.6.1 Interior Aircraft Noise. The FAA, in 1981, sponsored research to investigate the potential impact of interior aircraft noise on the crew and passengers of an aircraft (Ref. 2). The researchers concluded that the damage risk criteria of CHABA, discussed in the above paragraphs, is adequate for evaluation of potential hearing damage in both commercial and business jet-powered aircraft. Interior noise levels in both types of aircraft were tested, and none of the average levels in commercial or business jets exceeded the CHABA recommended levels. The study reports that less than 0.l% of the commercial and less than l% of business jets are expected to exceed damage risk contours. Given these small percentages, the researchers drew the following conclusions:

For the crew of an aircraft, long exposures to noise of as many as sixteen hours flight time should not present any problems as long as the average daily exposure is four hours. (Four hours is currently the maximum average daily amount flown in commercial jet aircraft.)

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1. Michael, P.L., 14.T. Anchor, G.R. Bienvenue et al. Community Noise Fundamentals: A Training Manual and Study Guide. Pennsylvania State University College of Education, June 1980.

2. Pearson, Karl S, and John F, l4ilby. "Possibility of Hearing Loss from Exposure to Interior Aircraft Noise." Ref. No. FAA-AEE-81-15, November 1981.

3. Parnell, Nagel, & Cohen, "Evaluation of Hearing Levels of Residents Living Near a Major Airport," Report FAA-RD-72-72, June 1972.

4. Ward, Cushing & Burns, "TTS From Neighborhood Aircraft Noise," Journal of Acoustical Society of America, Vol. 60, No. 1, July 1976.

5. Kabuto & Suzuki, "Temporary Threshold Shift from Transportation Noise," Journal of Acoustical Society of America, Vol. 66, No. 1, July 1979.

6. Occupational Safety and Health Administration, Code of Federal Regulations, Title 29, Chapter 27, Part 1910.

7. U.S. Environmental Protection Agency, "Information on Levels of Environmental Noise Requisite to Protect Public Health and Welfare with an Adequate Margin of Safety," EPA 550/9-74-004, March 1974.

8. U.S. Air Force Regulation 161-35, April 1982.

9. U.S. Air Force. Design Note 3F1, January 1974.

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Section 6.0 SPEECH INTERFERENCE

INTRODUCTION

Speech interference is a principal factor in human annoyance response. It can also be a critical factor in situations requiring a high degree of intelligibility essential to safety. This section contains a summary of research results useful in estimating the degree of speech intelligibility as a function of distance in various ambient noise environments. Criteria are also presented defining levels of intelligibility deemed acceptable (through experience) in various work situations.


AVIATION APPLICATIONS/ISSUES

1. Annoyance to aircraft noise

2. Interference with cockpit communication


GUIDANCE/POLICY/EXPERIENCE

1. Speech intelligibility is adequately assessed using single event noise measures such as ALm, SIL or PSIL.

2. Activities where speech intelligibility is critical include class room instruction, outdoor concerts and other leisure listening endeavors.

3. Advisory information for speech intelligibility in aircraft cockpit environment has been developed by the FAA.

4. Surveys of annoyance to aircraft noise reflect to a large extent reactions to activity interference very often associated with speech interference.

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6.1 INTRODUCTION

A major annoyance associated with aircraft noise is interference with verbal communication. This section discusses the various measures of speech intelligibility that have been developed, explains how to assess speech intelligibility and outlines the implications of speech interference for individuals on the ground and in the cockpit of an aircraft.

6.2 MEASURES OF SPEECH INTELLIGIBILITY

A number of noise metrics have evolved for assessing the influence of noise on speech.

1. The Preferred Speech Interference Level (PSIL) is defined as the arithmetic average of the sound pressure levels in the 500 Hz, 1000 Hz and 2000 Hz octave bands.

2. The Speech Interference Level (SIL) is defined as the arithmetic average of the sound pressure levels at the 500, 1000, 2000 and 4000 Hz octave bands.

3. The Articulation Index (AI) is a value, between zero and 1.0, which describes the masking of speech by background noise; this value is found by evaluating the signal to noise ratio in specific frequency bands. There are different methods specified for different bandwidths, depending on the resolution required. For example, a masking noise with a continuous spectrum can be evaluated with fewer points than a spectrum punctuated by sharp spikes and deep valleys. The AI can be adjusted upward through the use of visual cues. Figure 6.1 reflects the relation between the calculated AI and the effective AI for communications where the listener can see the lips and face of the talker. The AI is the most sophisticated and most accurate technique developed to assess speech

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5. A-Weighted Sound Level (AL), defined in Section 2.0, is found to correlate well with SIL and PSIL formostsounds associated with aviation.

6.3 ASSESSING SPEECH INTELLIGIBILITY

There are many ways to assess speech intelligibility using the methods discussed above. Various tables exist throughout speech interference

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literature which relate AI levels, SIL and PSIL to levels of speech intelligibility. Table 6.1 is one example of such a table; it relates speech interference levels to levels of effective communication. Figure 6.3 provides the permissible distance between a speaker and listeners for specified voice levels and ambient noise levels, using AL (referred to in the table as dBA).

Another helpful interpretive scheme has been developed by the U.S. Army, which has determined through research and experience the levels of speech or sentence intelligibility appropriate for various workspaces. Table 6.2 depicts the relationship between NC values and speech quality.

6.4 SPEECH INTERFERENCE ON THE GROUND

Speech interference associated with aircraft noise is a primary source of annoyance to individuals on the ground. The disruption of leisure activities such as listening to the radio, television, music and conversation gives rise to frustration and irritation. Quality speech communication is obviously also important in the classroom, office and industrial settings. In one 1963 study, sponsored by the British government, researchers found that aircraft noise of 75 dB annoyed the

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1. Peterson, Arnold P.G. Handbook of Noise Measurement. GenRad, Inc., 1980.

2. U.S. Air Force. Design Note 3F1. January 1974.

3. Great Britain Committee on the Problem of Noise. Noise, Final Report. Presented to Parliament by the Lord Minister for Science by Command of Her majesty. London, H. M. Stationery Office, July 1963.

4. Industrial Audiology. Cockpit Communication Interference. FAA Order Number DTAFAO1-82-81561; July 1982.

5. FAA Advisory Circular Draft on Cockpit Speech Interference.

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INTRODUCTION

This section describes the sleep process and reviews research relating the percentage of an exposed population experiencing awakening to noise level. Design criteria are also identified for avoiding unacceptable rates of awakening.

AVIATION APPLICATIONS/ISSUES

Sleep interference associated with aircraft noise.

GUIDANCE/POLICY/EXPERIENCE

Sleep interference is one of the factors contributing to aircraft noise annoyance. Airport nighttime restrictions have been employed to minimize this annoyance. In the case of nighttime operations an exterior maximum sound level (ALm) of 72 dB is identified as an acceptable sleep interference threshold for windows closed condition. This corresponds to an interior ALm of about 55 dB.

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7.3.1 Arousal from Sleep. The study revealed that, while research has yielded widely varying conclusions as to what the threshold of arousal from sleep is, the level of a noise which can interfere with falling or waking from sleep ranges from 35 to 70 dB. The varied results of researchers arise because several factors affect how easily a person will be awakened from sleep. As mentioned above, a person's age is a prominent factor affecting arousal. Children sleep the heaviest, the elderly the lightest, sleep. Thus, older people have a much lower , arousal threshold than do younger people.

As one might expect, there is also a rise in the threshold of arousal as sleep stages deepen. The average difference in the arousal threshold from being awake to stage 4 NREH sleep is about 17.5 dB. Lastly, because of the cyclical nature of the two sleep stages (REM and NREM), an individual's susceptibility to arousal varies throughout the night. However, in a normal 8-hour sleep night, more time is spent in lighter stages of sleep in the last half than in the first half. This implies that airport use restrictions limiting early morning flight from 3 a.m. to 7 a.m. are particularly important. Although people are also susceptible to arousal at the beginning of a sleep period when they are just trying to fall asleep, in general arousal is more likely during the late hours of sleep.

7.3.2 Measuring Sleep Interference. Some studies have shown generally that the single event energy dose of a noise event (EPNL or SEL), and not the maximum level (in PNL or AL) is a better predictor of sleep interference (Refs. 4, 5). These findings have been contradicted in a report by 0hrstrom and Rylander, who assert that peak levels should be used to determine tolerable night levels of noise (Ref. 6). Researchers continue to debate this question.

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1. Kales A, and J. Kales. Evaluation and Treatment of Insomnia. New York, Oxford University Press, 1984.

2. Griefahn, Barbara. Research on Noise-Disturbed Sleep Since 1973. In Proceedings of the Third International Congress on Noise as a Public Health Problem. ASHA Report No. 10, April 1980.

3. Kryter, Karl. D., Analysis of Laboratory and Field Data on Awakening from Noise.

4.Lukas, J., Measures of Noise Level: Their Relative Accuracy in Predicting Objective and Subjective Responses to Noise During Sleep. EPA-600/1-7-010, U.S. Environ. Protect., Agency. Feb. 1977.

5. Horonjeff, R., R. Bennett, and S. ________, Sleep Interference BBN Rpt. 3710 Dec. 1978, Electric Bower Research Institute, Inc., Palo Alto, CA 94302.

6. 0hrstrom, E., and R. Rylander, Sleep Disturbance Effects of Traffic Noise - A Laboratory Study on After Effects, J. Sound and Vib. Vol. 84, 1982, pp. 87-103.

7. LeVere, T. G. Morlock and F. Hart, Waking performance decrements following minimal sleep description: The effects of habituation during sleep, Physiological Psychology, Vol. 3, 1975, pp. 147-174.

8. Ando, Y. and H. Hatton, Effects of Noise on Sleep of Babies, J. Acoust. Soc. Am. Vol. 62, 1977, pp. 199-204.

9. Reported in Kryter, K. D., Community Annoyance from Aircraft and Ground Vehicle Noise, J. Acoust. Soc. Am. Vol. 72, 1982, pp. 1222-1242.

10. Wyle Labs, Res. Staff. Study of Soundproofing Public Buildings Near Airports. Ref. No. DOT-FAA-AEQ-77-9, April 1977.

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INTRODUCTION

This section summarizes a series of contemporary research studies which hypothesize correlation between noise exposure in general (in many cases aircraft noise exposure) and various human physiological or behavioral effects. While some studies show a significant correlation, other studies show none. Although research continues, there does not exist a succession of studies which corroborate the "cause and effect" theory. While the reader should be aware of research in this area, the topics reviewed in this section are considered to be beyond the realm of normally accepted and recognized aircraft noise effects.

AVIATION APPLICATION/ISSUES

1. Cardiovascular effects

2. Achievement scores

3. Birth weight

4. Mortality rates

5. Psychiatric admissions

GUIDANCE/POLICY/EXPERIENCE

1. As cited above the relationship between these suggested "effects" and aircraft noise has not been repeatedly and consistently demonstrated. On the contrary, many studies directly contradict those which show an effect.

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1. U.S. Environmental Protection Agency, "Information on Levels of Environmental Noise Requisite to Protect Public Health and Welfare with an Adequate Margin of Safety," EPA 550/9-74-004, March 1974.

2. People Against Nuclear Energy v. U.S. Nuclear Regulatory Commission U.S. Court of Appeals for the District of Columbia, May 14, 1982.

3. Wesler, John F. Unpublished Information Paper on the Effects of Noise. Federal Aviation Administration, AEE-120, Washington, D.C., 1981.

4. Thompson, "Epidemiology Feasibility Study: Effects of Noise on the Cardiovascular System," EPA Report 550/9-81-103, September 1981.

5. Meecham & Shaw, "Effects of Jet Noise on Mortality Rates," British Journal of Audiology, Vol. 13, 1979.

6. Frerichs, Beeman & Coulson, "Los Angeles Airport Noise and Mortality - Faulty Analysis and Public Policy," American Journal of Public Health, Vol. 70, No. 4, April 1980.

7. Jones & Tauscher, "Residence Under an Airport Landing Pattern as a Factor in Teratism," Archives of Environmental Health, Vol. 33, 1978.

8. Edmonds, Layde & Erickson, "Airport Noise and Teratogenesis," Archives of Environmental Health, Vol. 34, pp. 243-247, 1979.

9. Meecham & Smith, "Effect of Jet Aircraft Noise on Mental Hospital Admissions," British Journal of Audiology, Vol. ii, pp. 81-85, 1977.

10. Gattoni & Tarnopolsky, "Aircraft Noise and Psychiatric Morbidity," Psychological Medicine, Vol. 3, pp. 516-520, 1973.

11. Knipschild, "V. Medical Effects of Aircraft Noise: Community Cardiovascular Survey," International Archives of 0ccupational and Environmental Health, Vol. 40, 1977.

12. Knipschild, "VI. Medical Effects of Aircraft Noise: General Study," International Archives of 0ccupational and Environmental Health, Vol. 40, 1977.

13. Knipschild, "VII. Medical Effects of Aircraft Noise: Drug Survey," International Archives of Occupational and Environmental Health, Vol. 40, 1977.

14. Knipschild, "VIII. Medical Effects of Aircraft Noise: Review and Literature," International Archives of Occupational and Environmental Health, Vol. 40, 1977.

15. Charles Frances Davison et. al. v. Department of Defense et. al., U.S. District Court for Southern District of Ohio, May 1982.

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INTRODUCTION

This section summarizes research concerning the effects of aviation noise on wild mammals, birds and fish, on farm animals (swine, cattle, poultry and mink), and on a variety of laboratory animals. While a significant amount of research has been conducted on the reactions of animals to noise, it has proven difficult to draw any general conclusions on the subject because there is much variability in response both between and within species. Thus, no clear policies or guidelines have been developed concerning noise exposure and animals.

AVIATION APPLICATION/ISSUES

1. Harm to animals in U.S, wildlife refuges, national parks, and wilderness areas

2. Effects on the productivity of domestic animals


GUIDANCE/POLICY/EXPERIENCE

Animals are rarely exposed to high noise levels outside of the laboratory, and most have proven impervious to the aircraft noise they do experience. Nevertheless, a few species have demonstrated little tolerance of aircraft noise and have shown few signs of adapting to it. Since no well-established guidelines concerning noise and animals exist, it is important to remain aware of the issue and alert to the possibility that "off-limits" wildlife areas may be desirable in the future for selected wildlife areas.

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A 1963 study found that pigs exposed to recorded jet and propeller aircraft sounds of 120 to 135 dB daily from 6 a.m. to 6 p.m. from weaning time or before, until slaughter at 200 pounds body weight, showed no differences in feeding or weight gain from pigs unexposed to the sounds (Ref. 5).

Another study also reported that dairy cattle showed no differences in milk production when exposed to aircraft noise. The researchers compared milk cow herds located within three miles of a number of air force bases using jet aircraft (13 percent of the herds were within 1 mile of the end of an active runway). Dairy cattle studied in the vicinity of Edwards Air Force Base (California) showed few abnormal behavioral reactions due to sonic booms, though they had been exposed to the booms for several years and so may have become habituated (Ref. 6). Other studies also supported this evidence that cattle are generally not affected by the sonic boom or other aircraft noise.

Poultry have shown no more reaction to aircraft noise than swine or cattle. In a 1958 study, recorded aircraft flyover noise at 80 to 115 dB at 300 to 600 Hz was played daily and every third night from the beginning of the hens brooding until the chicks were 9 weeks old. There resulted no difference in weight gain, feeding efficiency, meat tenderness or yield, or mortality between sound-exposed and non-exposed chicks (Ref. 7). Broad breasted bronze turkeys were exposed to recordings of low flying jet planes at l10 to 135 dB for 4 minutes during the third day of brooding. The turkeys typically ceased brooding but resumed it shortly, with no decrease in egg laying (Ref. 8). A final study showed that chicken eggs exposed to daily sonic booms for 21days during their incubation hatched normally (Ref. 9).

In a 1968 study on mink, one hundred twenty animals were exposed to simulated sonic booms ranging from 2.0 to 0.5 lb per sq ft. The litters of mink exposed to the booms were larger than those of mink not exposed. No racing, squealing or other signs of panic were observed in the animals. Animals that died naturally were examined; no disorders which could be traced to the sonic booms were found (Ref. 10). Female mink showed little or no response to exposure to sonic boom during breeding, birth of kits, or whelping. Again, no signs of panic were observed.

9.4 LABORATORY ANIMALS

Mice, rats, monkeys, and rabbits have been examined in numerous studies, the results of which are briefly reviewed here (Ref. 11). The studies generally exposed the test animals to a certain level of noise for a predetermined period of time; response was measured in terms of physiological change. Increases and decreases in body chemicals and in the weights of body organs were typically observed in the tests. Although some of the bodily changes were typical of reactions to stress (and noise is often considered stressful), it was not clear that the changes were significant or dangerous. As with humans, hearing damage occurred when the animals were exposed to high level noise; however, animals are rarely exposed to extreme aircraft noise.

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1. Edwards, Richard G., Alvin B. Broderson, Roger W. Barbour et al. Assessment of the Environmental Compatibility of Differing Helicopter Noise Certification Standards. U.S. Department of Transportation, FAA, June 1979.

2. International Civil Aviation 0rganization, Sonic Boom Committee. Report. . First meeting, Montreal, ICAO Doc. 9011, SBC/1, May 1972.

3. International Civil Aviation 0rganization, Sonic Boom Committee. Report. Second meeting, Montreal, ICAO Doc. 9064, SBC/2, June 1973.

4. U.S. Department of Transportation, FAA. Concorde Supersonic Transport Aircraft: Final Environmental Impact Statement. Vol. 1, September 1975.

5. Bond, J. C.F. Winchester, L.E. Campbell, and J.C. Webb. Effects of Loud Sound on the Physiology and Behavior of Swine. U.S. Department of Agriculture, Agricultural Research Service Technical Bulletin, No. 1280.

6. Parker, J.B, and N.D. Bayley. Investigations on Effects of Aircraft Sound on Milk Production of Dairy Cattle, 1957-1958. U.S. Department of Agriculture, Agricultural Research Service, Animal Husbandry Research Division, 1960.

7. Stadelman, W.J. The Effects of Sounds of Varying Intensity on Hatchability of Chicken Eggs. Poultry Science, 37, 1958.

8. Jeannoutot, D.W. and J.L. Adams. Progesterone Versus Treatment by High Intensity Sound as Methods of Controlling Broodiness in Broad Breasted Bronze Turkeys. Poultry Science, 40, 1961.

9. Bell, W.B. Animal Response to Sonic Boom. Paper presented at the 80th meeting of the Acoustical Society of America, Houston, November 1970.

10. Travis, H.F., G.V. Richardson, J.R. Menear, and J. Bond. The Effects of Simulated Sonic Booms on Reproduction and Behavior of Farm-Raised Mink. ARS 44-200, U.S. Department of Agriculture, Agricultural Research Service, June 1968.

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INTRODUCTION

This section reviews the effects of strong low frequency acoustical energy in creating some of the more unusual (albeit rare) aircraft noise effects. The consideration of low frequency sound in creating vibration (and secondary noise) in structures is discussed. While structural vibration is not a common concern for commercial transport airplanes, there may be some need to exercise caution in helicopter operations in close proximity to buildings. A brief review is also provided addressing human physiological reactions to intense low frequency sound as one might encounter near engine test stands. Criteria are presented for both annoyance to vibration and human physical damage risk for exposure to intense infrasound.

AVIATION APPLICATIONS/ISSUES

1. Vibration of wall and windows

2. Radiation of secondary noise

3. Human physiological response to intense low frequency
sound

4. Sonic Booms (illegal in U.S, for civil aircraft
operations)

GUIDANCE/POLICY/EXPERIENCE

The issue of low frequency energy and its impact on buildings and people was explored in detail in regard to the Concorde SST operations in the U.S. Impacts were found to be negligible. Consequently low frequency effects from civil commercial aircraft remains a minor issue in most environmental impact assessments. There remains the need however to consider carefully possible effects of low frequency energy in the operation of helicopters in close proximity to buildings.



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worst case example, the Concorde supersonic transport creates sound pressure levels at low frequencies (below 30 Hz) which are well below EPA sensation and damage risk levels. All other commercial transport levels fall below those of the Concorde, indicating no potential health effects associated with low frequency noise from in-service commercial aircraft.

10.5.2 International Standards 0rganization (ISO). Generally, human tolerance of vibration is lowest in the 4-8 Hz frequency range, and this is the basis of limits proposed by the ISO Technical Committee 108 working Group. Human tolerance to vibration also depends on situational factors; for example, the blurring of vision which is merely an annoyance to a train passenger could impair safety and efficiency in the workplace. It is also not known to what extent non-auditory sensations of noise are symptoms of psychological stress.

10.6 SONIC BOOM

FAA flight rules require civil aircraft to fly at subsonic speed over U.S. land areas in order to prevent sonic booms from impacting the U.S. environment. For supersonic aircraft approaching or leaving U.S. boundaries, flight rules stipulate that the aircraft be operated in a manner that will not cause direct sonic shock waves to encroach upon the U.S. (Ref. 6).

Sonic booms result when a projectile such as an aircraft exceed the speed of sound. The phenomenon we call a boom is similar in many ways to an explosion, characterized by a rapid increase in pressure above the ambient pressure, followed by a negative pressure excursion. An example of this N-wave signature is shown in Figure 10.3.

A great deal of research was conducted in the1950's and 1960's by the U.S. Air Force and prospective manufacturers of the an American SST. (The U.S. SST program was eventually cancelled). The relationships

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One of the most famous studies on the sonic boom was conducted in 1964 over Oklahoma City (Ref. 8). Eight sonic booms a day at a median peak overpressure level of 1.2 psf (57.46 pascals) were experienced by this community over a six-month period. Figure 10.4, below, reveals the percentage of responding residents who reported adverse reactions to the sonic booms. Based on this and many other studies, the U.S. EPA has stated that "the peak overpressure of a sonic boom that occurs during the day should be no more than 35.91 pascals (0.75 psf) if the population is not to be annoyed or the general health and welfare adversely affected " (Ref. 9).

As a matter of interest, a rather unusual phenomenon called secondary sonic booms were observed shortly after the introduction of Concorde service to the U.S. In essence, sonic shock waves from the Concorde were refracting off the discontinuity at the top of the earth's atmosphere and bending back down to the earth, l4hile the level of the overpressures was not high enough to cause any damage, people did take notice. After a study of these "mystery booms" by the FAA / DOT (Ref. 10), the Concorde pilots implemented changes in their operational procedures to minimize the occurrences.

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Ref 8

10.7 CONCLUSION

As discussed in this section, low frequency sound and its effects are relatively minor considerations in assessing aircraft nose impact. The case of helicopter operations in close proximity to buildings, however, remains an area warranting close scrutiny.

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1. Hershey, Robert L., Russ J. Kevala, and Sharon L. Burns. Analysis of the Effect of Concorde Aircraft Noise on Historic Structures. Rep. No. FAA-RD-75-118, July 1975.

2. Wiggins, John H. The Influence of Concorde Noise on Structural Vibrations. Rep. No. FAA-75-1241-1, July 1975.

3. Schomer, Paul. The Role of Vibration and Rattle in Human Response to Helicopter Noise. Unpublished Report, December 1986.

4. Douglas Aircraft Company, Long Beach CA. Sonic Boom Modeling Investigation of Topographical and Atmospheric Effects. Final Report, FAA-NO-70-l0, July 1970.

5. U.S. Environmental Protection Agency, Office of Noise Abatement and Control, Washington D.C. Information on Levels of Environmental Noise Requisite to Protect Public Health and Welfare with an Adequate Margin of Safety. March 1976.

6. Code of Federal Regulations, FAR 91.55.

7. Federal Aviation Administration, Office of Planning. Some Considerations of Sonic Boom. May 1961.

8. Borsky, P.N. Community Reactions to Sonic Booms in the Oklahoma City Area. National Opinion Research Center, AHRL-TR-65-37, 1965.

9. U.S. Environmental Protection Agency. Information on Levels of Environmental Noise Requisite to Protect Public Health and Welfare with an Adequate Margin of Safety. 550/9-74-004, March 1976.

10. Rickley, Edward J, and Allan D. Pierce. Detection and Assessment of Secondary Sonic Boom in New England. FAA-AEE-80-22, May 1980.

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INTRODUCTION

Over the past 10 years, researchers in aviation acoustics have suggested that penalties be assessed (dB increments added) for sounds which possess impulsive characteristics. Helicopter blade slap which accompanies certain modes of flight operation has been the primary subject of this research. This section reviews the research. and, as elsewhere, finds conflicting results. While some researchers find the need for an adjustment others do not. Complex distinctions between detectability and annoyance are key to the debate. In the end, the position adopted by the International Civil Aviation Organization (ICAO) was that no correction is necessary.. Nonetheless, the Helicopter Association International (HAT), and the FAA continue to conduct research to minimize impulsive helicopter noise.

AVIATION APPLICATION/ISSUES

The question is raised, in connection with helicopter noise, whether or not an impulsivity correction is necessary to properly assess human reaction.

GUIDANCE/POLICY/EXPERIENCE

After years of research, ICAO concluded that an impulsivity adjustment was unnecessary to properly certificate aircraft; this, in effect, implies that human response is adequately assessed without a special impulsivity adjustment to the EPNL metric. Nonetheless efforts continue to reduce impulsive noise which dominates helicopter noise in certain flight regimes.

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1. Wright, S.E, and A. Damongeot. Psychoacoustic Studies of Impulsive Noise. Paper #55, Third European Rotorcraft Powered Lift Aircraft Forum, Aeronautical and Astronautical Association of France, September 1971.

2. Patterson, James, Ben T. Mizo, Paul D. Schemer, Robert T, Camp. Subjective Ratings of Annoyance Produced by Rotary-Wind Aircraft Noise. U.S. Army Aeromedical Research Laboratory, Report No. 77-12. May 1977.

3. Powell, Clemans A. A Subjective Field Study of Helicopter Blade-Slap Noise. NSA Technical memorandum 78758, July 1978.

4. Loughborough University of Technology. Studies of Helicopter Noise Perception: Background Information Paper. ICAD Committee on Aircraft Noise, Working Group B, December 1981.

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INTRODUCTION

The issue of whether noise occurring at different times of the day should be assigned weighting factors to represent different human sensitivity to noise intrusion has been a subject of much concern and research over the past 35 years. This section briefly reviews the research and practice. The metric selected by the FAA as the standard for use in airport noise impact assessment uses a 10 dB nighttime weighting factor.

AVIATION APPLICATON/ISSUES

1. Should aircraft noise occurring in the evening or at nighttime be assigned a weighting penalty to account for increased sensitivity to noise intrusions?

2. If a weighting is appropriate, what is the value of the weighting function?

GUIDANCE/POLICY/EXPERIENCE

The FAA has designated the Yearly Average Day Night Sound Level as the metric for assessing airport cumulative noise impact. This metric assigns a 10 dB weighting between the hours of 10 p.m. and 7 a.m.


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Various recommendations were offered by conference participants concerning DNL. The representatives of several governmental agencies spoke in favor of maintaining agreement between Federal agencies as to what metric to use; they also stated a desire to have that metric be one that is applicable to all kinds of noise, (i.e. traffic, background, aircraft) which DNL is. Other recommendations from conference discussion groups and individuals included the following:

1. Researchers were urged to reconsider changing lifestyles and to reflect on whether 10 PM to 7 AM is the most sensitive portion of the day. Evening or transition may be more important.

2. DNL should remain a rough screening device. The DNL penalty, for example, could impact school operations if a large number of operations were shifted to the day. The public is urged to pursue local independent decisions on this matter.

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• people report at least one awakening per night regardless of the presence or absence of noise
  
• actual sleep disturbance and people's report of sleep disturbance is weakly related
  
• people's reported annoyance/disturbance did not decrease after actual flights were reduced.
  
• People's age and sex both seem to partially determine how much and how easily a person is awakened at night.
  

There is also the possibility that people's perception of and annoyance with daytime noise affects their perception of nighttime noise, some researchers feel that there may be more complaints about nighttime noise because people view it as a more valid complaint than something like television disruption; thus, the perspective on time-of-day may be skewed. One study suggested that daytime activities, which usually involve communicating or concentrating tasks, might be more sensitive to interruption than sleep.

The report stated that the one point that researchers seem to agree on -- although again, empirical evidence is scant -- is that the most annoying/disturbing times for noise to occur are when a person is trying to go to sleep and when he is preparing to awaken. However, bedtime

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1. Workshop Proceedings, NASA Langley Research Center. Time of Day Corrections to Aircraft Noise Metrics. Rep. No. FAA-EE-80-3, March 1980.

2. Fields, James M. Research on the Effect of Noise at Different Times of Day: Models, Methods and Findings. Unpublished Report, August 1984.

3. Pearson, K. S. The Effects of Duration and Background Noise level on Perceived Noisiness. FAA ADS-78, Federal Aviation Administration, April 1966.

4. Taylor S. M., F. L. Hall and S. E. Bernie. ?Effect of Background Levels on community Responses to Aircraft Noise, J. Sound & Vib, Vol. 71, No. 2, July 22, 1980.

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INTRODUCTION

Noise contours or footprints are the accepted technique for displaying airport cumulative noise exposure. Noise contours are also employed in comparing the noise footprints of individual aircraft. Contours can be developed for different noise indices, but airport contours generally express DNL while individual aircraft contours usually portray either SEL, EPNL or ALm.


AVIATION APPLICATION/ISSUES

1. Contours are used as the tool to assess land use compatibility.

2. Contours are also used to portray the noise exposure of single operations of various aircraft types.


GUIDANCE/POLICY/EXPERIENCE

The noise contour program developed by the FAA and approved for use in FAA funded airport land use compatibility studies is the Integrated Noise Model or INM. This program can also generate single event contours. A new microcomputer-based model which will generate noise contours for helicopters is now under development.



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INTRODUCTION

This section describes the development of criteria linking cumulative airport noise exposure and compatible land use. Criteria are presented which have been designated for use in FAA funded compatibility studies.


AVIATION APPLICATION/ISSUES

1. FAR PART 150, Airport Noise Compatibility Programs

2. Planning guidance for developers and zoning officials.

3. Guidance for the granting of HUD and VA mortgage
guarantees.

4. Airport master plans.

5. Environmental Impact Assessments


GUIDANCE/POLICY/EXPERIENCE

The FAA has published criteria in FAR PART 150 for use in compatibility studies. Other similar criteria have been published by the Department of Defense, the Federal Interagency Committee on Urban Noise, and the American National Standards Institute (ANSI).

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Land Use	ANSI Standard	FAA Standard
Livestock Farming	Compatible to 65 dB Marginally compatible to 75 dB Incompatible above 75 dB	Compatible to 75 dB
General Manufacturing	Compatible to 70 dB Marginally to 80 dB Incompatible above 80 dB	Compatible to 85 dB Incompatible above 85 dB
Music Shells	Marginally to 65 dB	Compatible to 64 dB
Playground, Riding, Golf	Compatible to 60 dB Marginally to 75 dB Incompatible above 75 dB	Compatible to 70 dB Compatible with special details up to 80 dB

14.3 FEDERAL INTERAGENCY CRITERIA

Guidelines for considering Noise in Land use Planning and Control was published in June 1980 by the Federal Interagency Committee on Urban Noise. This Committee is comprised of representatives from the Departments of Defense, Transportation and Housing and Urban Development, the Veterans' Administration and the Environmental Protection Agency, the five Federal agencies most involved in noise, land use, or environmental policy. Without overriding any agency's existing policies or regulations, the Guidelines provide a foundation for an integrated Federal system of noise/land use policy. As a consequence, FAA, DOD and HUD policy and regulations relative to airport noise and housing are quite compatible.

The Interagency document also contains a summary of the many techniques that local governments can use to reduce the effect of noise on surrounding land uses. These techniques range from simply increasing public awareness of noise levels, to developing land use codes and zoning policies, to the drastic but effective measure of public purchase of severely exposed land.

14.4 DEPARTMENT OF DEFENSE AICUZ CRITERIA

The Department of Defense has also developed a comprehensive program to minimize the harmful effects of aircraft noise (Ref. 4). The Air Installation compatible Use Zones (AICUZ) program requires that all military installations be studied in depth to determine those land areas which should be specially considered in development because they are

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Numbers in parentheses refer to notes.

*The designations contained in this table do not constitute Federal determination that any use of land covered by the program is acceptable or unacceptable under Federal, State or local law. The responsibility for determining the acceptable and permissible land uses and the relationship between specific properties and specific noise contours rests with the local authorities. FAA determinations under Part 150 are not intended to substitute federally determined land uses for those determined to be appropriate by local authorities in response to locally determined needs and values in achieving compatible land uses.

KEY TO TABLE 1
SLUCM = Standard Land Use Coding Manual
Y(Yes) = Land Use and related structures compatible without restrictions.
N(No) = Land Use and related structures are not compatible and should be prohibited.
NLR = Noise Level Reduction (outdoor to indoor) to be achieved through incorporation of noise attenuation into the design and construction of the structure.
25, 30, or 35 = Land use and related structures generally compatible; measures to achieve NLR of 25, 30, or 35 dB must be incorporated into design and construction of structures.

NOTES FOR TABLE 1

(1) Where the community determines that residential or school uses must be allowed, measures to achieve outdoor to indoor Noise Level Reduction (NLR) of at least 25 dB and 30 dB should be incorporated into building codes and be considered in individual approvals. Normal residential construction can be expected to provide a NLR of 20 dB, thus, the reduction requirements are often stated as 5, 10, or 15 dB over standard construction and normally assume mechanical ventilation and closed windows year round. However, the use of NLR criteria will not eliminate outdoor noise problems.

(2) Measures to achieve NLR 25 dB must be incorporated into the design and construction of portions of these buildings where the public is received, office areas, noise sensitive areas or where the normal noise level is low.
(3) Measures to achieve NLR of 30 dB must be incorporated into the design and construction of portions of these buildings where the public is received, office areas, noise sensitive areas or where the normal noise level is low.
(4) Measures to achieve NLR of 35 dB must be incorporated into the design and construction of portions of these buildings where the public is received, office areas, noise sensitive areas or where the normal noise level is low.
(5) Land use compatible provided special sound reinforcement systems are installed.
(6) Residential buildings require an NLR of 25.
(7) Residential buildings require an NLR of 30.
(8) Residential buildings not permitted.

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1. American National Standard. Sound Level Description for Determination of Compatible Land Use. Rep. No. ANSI S3.23-1980, 1980.

2. FAA Code of Federal Regulations, Part 150.

3. Federal interagency Committee on Urban Noise. Guidelines for Considering Noise in Land Use Planning and Control. June 1980.

4. U.S. Air Force. Manual 19-10. Planning in the Noise Environment. Chapter 4.

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INTRODUCTION

This section reviews research conducted to assess the effect of aircraft noise on real estate values. While an effect is observed it is considered an influence which is often offset by the advantages associated with ready access to the airport and employment opportunities.

AVIATION APPLICATION/ISSUES

The effect of aircraft noise on real estate values is a topic often associated with environmental assessments.

GUIDIANCE/POLICY/EXPERIENCE

Studies indicate that a one decibel change in cumulative airport noise exposure (in DNL) usually results in a 0.5 to 2% decrease in real estate values.

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*The NDI-NEF is the percentage decrease in a given property value per unit increase in the DNL


Nelson found that the studies can be divided into two groups and some conclusions drawn. The first group of estimates in the table was based on 1960 data (and included New York, Los Angeles and Dallas) and suggests a range of 1.8 to 2.3 percent decrease in value per decibel (DNL). The second group of estimates, covering the period from1967 to 1970, suggests a mean of 0.8 percent devaluation per decibel change in DNL. Nelson then excludes the San Francisco data (which was influenced by unique climatic and political differences) and finds a mean of 0.7 percent devaluation per decibel change in DNL.

Nelson also notes that there seems to be a decline in the noise depreciation index over time, from 1960-1970. This could be due either to noise sensitive people being replaced by those less bothered by noise, or to the enhanced commercial value of land near airports. Evidence exists to support either of these hypotheses (Ref. 2).


15.4 CONCLUSION

The bottom line is that noise has been shown to decrease the value of property by only a small amount -- approximately 1% decrease per decibel (DNL). At a minimum, the depreciation of a home due to aircraft noise is equal to the cost of moving to a new residence. Because there are many other factors that affect the price and desirability of a residence, the annoyance of aircraft noise remains just one of the considerations that affect the market value of a home.

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1. Nelson, Jon P. Economic Analysis of Transportation Noise Abatement. Ballenger Publishing Company: Cambridge, Massachusetts, 1978.

2. Crowley, R. W. A Case Study of the Effects on an Airport on Land Values. Journal of Transport Economics and Policy, Vol. 7, May, 1978.

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