ASTM E1503-22

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E1503 − 22
Standard Test Method for
Conducting Outdoor Sound Measurements Using a
Statistical Sound Analysis System
This standard is issued under the fixed designation E1503; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
This is one of a series of standards on the measurement and evaluation of community noise. Others
in the series include Guide E1014 which covers manual measurement, using a simple meter, and
analysis of the resulting data, and Guide E1780, which covers measurement of sound received from
a nearby fixed source.
1. Scope possible, with all the applicable requirements of this test
method, including record keeping.
1.1 This test method covers the measurement of outdoor
sound levels at specific locations using a digital statistical 1.4 The data obtained using this test method enable com-
sound analysis system and a formal measurement plan. parison of sound level data with appropriate criteria.
1.1.1 This test method provides basic requirements for 1.4.1 The data obtained with this test method can be used in
obtaining either a single set of data or multiple sets of related the derivation of loudness levels provided the necessary
data. However, because there are numerous circumstances and requirements regarding sample duration and signal bandwidth
varied objectives requiring multiple sets of data, the test are observed in collecting the data. It is recommended that a
method does not address planning of the measurement pro- specialist in the area of loudness evaluation be consulted in
gram. preparing a plan for measurements intended to produce data
which will be used for this purpose.
1.2 Theuseofresultsofmeasurementsperformedusingthis
test method include, but are not limited to, the following: 1.5 The values stated in SI units are to be regarded as
1.2.1 To characterize the acoustical environment of a site, standard. No other units of measurement are included in this
1.2.2 To characterize the sound emissions of a specific standard.
sound source which exhibits a temporal variation in sound
1.6 This standard does not purport to address all of the
output, and
safety concerns, if any, associated with its use. It is the
1.2.3 To monitor the effectiveness of a noise impact miti-
responsibility of the user of this standard to establish appro-
gation plan.
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
1.3 This test method is intended to be used in conjunction
1.7 This international standard was developed in accor-
with a measurement plan that references this test method.
dance with internationally recognized principles on standard-
Changes or additions to the provisions of this test method shall
ization established in the Decision on Principles for the
be clearly stated in the plan.
Development of International Standards, Guides and Recom-
1.3.1 In the event it is necessary, for example, because of
mendations issued by the World Trade Organization Technical
time constraints, to conduct measurements without first for-
Barriers to Trade (TBT) Committee.
malizing a plan, this test method can be used if an operator/
observer whose qualifications are satisfactory to both the
2. Referenced Documents
performing organization and the client is present at all times
during the measurements and who complies, to the extent
2.1 ASTM Standards:
C634 Terminology Relating to Building and Environmental
Acoustics
ThistestmethodisunderthejurisdictionofASTMCommitteeE33onBuilding
and Environmental Acoustics and is the direct responsibility of Subcommittee
E33.09 on Community Noise. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Oct. 1, 2022. Published November 2022. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1992. Last previous edition approved in 2014 as E1503 – 14. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/E1503-22. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1503 − 22
E1014 Guide for Measurement of Outdoor A-Weighted 4.2.1 Documentationofsoundlevelsbeforetheintroduction
Sound Levels of a new sound source as a reference for assessment of the
E1686 Guide for Applying Environmental Noise Measure- noise impact caused by a proposed facility and associated
ment Methods and Criteria activities,
E1780 Guide for Measuring Outdoor Sound Received from
4.2.2 Comparison of sound levels with and without a
a Nearby Fixed Source specific source (for example, assessment of the impact of an
existing source), and
2.2 ANSI Standards:
4.2.3 Comparison of sound levels with criteria or regulatory
S1.11 SpecificationsforOctave-bandandFractionalOctave-
limits (for example, indication of exceedance of criteria or
band Analog and Digital Filters
non-compliance with laws).
S1.13 Measurement of Sound Pressure Levels in Air
S1.17 Microphone Windscreens - Part 1: Measurements and
4.3 Thistestmethodprovidesameansforoperatingasound
Specification of Insertion Loss in Still or Slightly Moving
analysis system which incorporates digital circuits for process-
Air
ingandstoringsoundleveldata,documentingconditionsunder
S1.40 Specification for Verification Procedures for Sound
which the measurements were performed, and reporting the
Calibrators
results.
S1.43 Specifications of Integrating-Averaging Sound Level
4.4 This test method provides the user with information to
Meters
(1) perform and document statistical analysis of outdoor sound
S12.9 Standard Quantities and Procedures for Description
level over specific time periods at specified places, and (2)
and Measurement of Environmental Sound, Part 2: Mea-
make and document the physical observations necessary to
surement of Long-Term, Wide-Area Sound and Part 3:
qualify the measurements.
Short-term Measurements with an Observer Present
2.3 IEC Standards 4.5 This test method can be used by individuals, regulatory
agencies, or others as a measurement method to collect
61672–1 Electroacoustics - Sound Level Meters - Part 1:
Specifications acoustical data for many common situations. The data are
collected in a format determined by the capabilities of the
3. Terminology
equipment, equipment operational options selected, and by
post-processing options available.
3.1 For definitions of terms, including the following used in
this test method, see Terminology C634: dummy microphone,
4.6 The user is cautioned that there are many factors that
interference, impulsive sound, measurement plan, measure-
canstronglyinfluencetheresultsobtainedduringmeasurement
ment set, percentile level, self noise and time-average sound
of outdoor sound levels and that this test method is not
level.
intended to supplant the experience and judgment of experts in
the field of acoustics. This test method is intended to facilitate
3.2 Definitions of Terms Specific to This Standard:
communication between sound measurement professionals and
3.2.1 digital statistical sound analysis system—combination
individuals who are responsible for administering regulations,
of a sound level meter, either analog or digital, interfaced with
or are otherwise involved in decisions involving sound mea-
a digital data storage device, and a digital statistical analyzer,
surements. Measurements shall be performed only under the
forsamplingenvironmentalsoundlevelsoveraspecifiedtimed
direction of people who are experienced in the measurement
interval.
andanalysisofoutdoorsound,andwhoarethoroughlyfamiliar
3.2.1.1 Discussion—For the purposes of this test method, a
with the use of the equipment and techniques involved.
generic analyzer having the necessary features for the intended
measurement and meeting the requirements of ANSI S1.11,
4.7 This test method is only a measurement procedure and,
and ANSI S1.43 is assumed.
as such, does not address the methods of comparison of the
acquireddatawithspecificcriteria.Noproceduresareprovided
4. Significance and Use
within this test method for estimating the influences of two or
4.1 This test method deals with methods and techniques more simultaneously measured sounds. This test method can
which are well defined and which are understood by a trained be used, with an appropriate plan, in establishing compliance
acoustical professional. This test method has been prepared to when the measured data are below a specified limit, or
provide a standard methodology which, when followed, will conversely, establishing noncompliance when any of the data
produce results which are consistent with requirements of are above a specified limit.
government and industry, and which can be validated using
information gathered and documented in the course of the 5. Interferences
measurement program.
5.1 Measurements intended to provide detailed spectral and
4.2 There are numerous situations for which outdoor sound
temporal sound level data are subject to interferences from a
leveldataarerequired.Theseinclude,butarenotlimitedtothe
numberofsources.Themostsignificantofthesearementioned
following:
briefly in paragraphs 5.1 – 5.8.
5.2 Effects of Wind:
5.2.1 Wind may influence sound level measurements, even
Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
4th Floor, New York, NY 10036, http://www.ansi.org. with a windscreen in place. The windscreen recommended by
E1503 − 22
the manufacturer may not be adequate in quiet environments should be noted in the report.Any measurements in which data
with mild wind conditions, especially in environments where (otherthananarrativedescriptionoftheimpulses)areobtained
low frequency, ambient sound must be evaluated. With wind should require a prescription for the sampling rate, system
speeds of 20 km/h and a typical windscreen the resulting response, and other pertinent guidelines including reference to
A-weighted sound level due to the wind alone is 40-45 dB. appropriate measurement standards.
Wind speeds of 40 km/h result in measuredA-weighted sound
5.5 Care shall always be taken to position the microphone
levels due to wind alone of 60-65 dB. Manufacturers’ instruc-
away from acoustically reflective surfaces which are not
tions shall be followed with respect to meter limitations under
normally present at the location specified by the measurement
windy conditions. When wind speeds approach or exceed 20
plan. This includes any vehicle used in connection with the
km/h, headphones shall be used to monitor the sound level
measurement program. In the absence of guidance from a
meter output or the sound level meter indicator shall be
measurement plan, the microphone shall be placed away from
carefully observed to determine if fluctuations correspond to
anysuchacousticallyreflectivesurfacebyatleast2 ⁄2timesthe
wind speed or actual sound sources. Data obtained during
major dimension of that surface.
intervals when wind generated sound is influencing the mea-
5.6 Electromagnetic radiation from high voltage transmis-
surements shall not be used. No measurements shall be made
sion lines or strong television or radio signals may affect the
when steady wind speeds exceed 20 km/h. Propagation of
sound level meter indication. The operator should use caution
soundfromasourcewillbeinfluencedbythedirectionofwind
when these are nearby. Such electrical interference problems,
relative to the source and measurement positions. Measure-
when they occur, might result in wild and unexpected swings
ments may need to be taken at different times of the year in
of the sound level meter indicator or upward indications even
different wind conditions to fully identify the acoustical
when the instrument is turned off. The most effective way to
character of the environment.
detect these conditions and other anomalies is through moni-
5.2.2 In special circumstances requiring measurements with
toring headphones.
wind speeds higher than 20 km/h, such as a background sound
5.6.1 Noise from power lines can increase significantly with
level survey involving a wind turbine project, a large (not less
high humidity, especially during light rain.
than 175 mm) windscreen shall be used. A larger windscreen
will produce less low frequency windscreen noise near the
5.7 A non-electrical problem related to power lines is the
microphone. However, it is cautioned, that large, foam type
generation of sound by aeolian strumming, or buzzing or
windscreenscancauseadditionalattenuationofhighfrequency
rattling by wires which are not tightly secured to insulators
sound. A calibration adjustment may be required. See ANSI
nearapowerline.Inaquietruralenvironmentsuchsoundscan
S1.17.
often influence or even dominate the background level. This is
5.2.3 If maximum wind speeds are not addressed in the an example of a noise source which requires careful consider-
measurement plan, manufacturer’s instructions shall be fol-
ation when choosing a measurement location. For guidance in
lowed with respect to analyzer limitations under windy condi- determiningifsuchsoundsarepartoftheambientorconstitute
tions.
interference, determine if the sound is part of the ambient at a
5.2.4 Propagation of sound from a source will be influenced point for which the ambient is to be characterized. If it is, it
by the direction of the wind relative to the source and shall be measured. If the sound can be defined as an
measurement positions. In some situations it may be desirable interference, one which masks an area-wide baseline, the
to make such measurements at different times of the year in
measurement location shall be moved to a point at which the
different wind conditions to fully identify the acoustical contributionofthesourceisatalevelmorerepresentativeofits
character of the environment.
area-wide level. The only way to avoid such interference is to
avoid measurement locations close to power poles or lines
5.3 Effects of Moisture and High Humidity:
when the measurement plan does not require a specific
5.3.1 Measurable precipitation almost always influences
location.
outdoor sound levels. For example, tires rolling on a paved
surface produce higher sound levels when the pavement is wet. 5.8 Effects of Meteorological Conditions:
Fallen snow may affect the propagation of sound. Data
5.8.1 Temperature inversions, wind and other meteorologi-
obtained under such conditions shall be retained but carefully cal conditions may strongly influence the propagation of sound
marked so that these data may be used with caution in over long distances. Therefore, when sound from sources at
subsequent analysis. horizontal distances of about 300 m or more need to be
measured, it may be desirable to make measurements at
5.3.2 High relative humidity, generally over 90 %, can
influence certain preamplifiers and microphones, especially different times of the year in different weather conditions to
air-condenser microphones. Microphone manufacturer’s in- fully identify the acoustical character of the environment.
structions shall be followed under high-humidity conditions.
5.9 Effects of Wildlife and Insects:
5.4 For sources that emit impulsive sound, the accepted 5.9.1 At various times of the year, naturally occurring
measurement methods for impulsive sound according toANSI sounds from birds, frogs, or insects, including crickets and
S1.13, such as SEL to quantify individual impulse and time- locusts, may interfere or even dominate the ambient
average sound level to measure periods of time that include A-Weighted and some fractional octave band sound levels,
impulses, should be used to obtain accurate results. The especially during evening and night hours. Such sounds should
presence of impulsive sounds emitted by the source under test be noted in the report. Where possible, an effort may be made
E1503 − 22
to quantify or account for such influence by making measure- 6.1.3.3 Tripod, of the type normally used for supporting
ments at different times or different locations to document photographic equipment, a mast integral with the instrument
conditions with and without such naturally occurring interfer- shelter, or other support sufficiently strong to support the
ing sounds. Octave-band (or ⁄3 octave-band) data should be weight of the microphone and protective equipment mounted
gatheredwhenthisisaproblem.Thesedatacanbeusedduring on it, and which by virtue of its weight or attachment to the
post-processing to mathematically remove the effect of the ground is resistant to being upset by the wind or other
insect noise from the results. disturbances,
6.1.3.4 Bird Deterrent Accessory, known as a bird spike,
6. Apparatus used to prevent fouling of windscreens by roosting birds. It is
recommended that a bird-deterrent accessory, available from
6.1 Acoustical Measurements:
some microphone manufacturers, be installed on the wind-
6.1.1 Digital Statistical Sound Analysis System, Use a Type
screen.
1 or Type 2 integrating, or averaging sound level meter as
6.1.4 Acoustical Calibrator (required), with adapters neces-
defined by ANSI S1.43 and IEC 61672–1, with statistical
sary to fit the microphone, meeting ANSI S1.40.
analysis capability and with a dynamic range of at least 60 dB.
6.1.5 Headphones—Headphones for monitoring the a-c out-
Thesystemshallhaveoneormoreofthefollowingcapabilities
put of the sound level meter portion of the analyzer shall have
as needed for a specific measurement plan:
the ability to exclude external sound. The headphones, with an
6.1.1.1 Selectable exponential time averaging (fast, slow),
appropriate battery-powered driver, shall have sufficient fre-
6.1.1.2 Ability to be interfaced with a portable computer or
quency response to permit detection of anomalies in the data
programmable calculator which can function as the controller,
caused by wind, humidity, and electrical interference. A
data storage, or analysis device,
frequencyresponseof50to20 000Hzshouldbeadequate.The
6.1.1.3 Ability to be programmed to perform specific types
headphonesshallbecorrectlymatchedtothesourceimpedance
of measurements and store the data within the analyzer,
of the output terminals.
6.1.1.4 Computation of values of sound level descriptors, or
Warning—Exercise care when using headphones with
permanent storage of data for later processing,
sound level meters since some meters and headphones are not
6.1.1.5 Weighting filters, that is, A, C,
compatible without the use of an impedance matching ampli-
6.1.1.6 Frequency-domain filters, for example, fractional
fier. Failure to use such an amplifier, when needed, may
octave-bands such as 1/1, 1/3 . 1/n octave, etc.,
damage the meter, or cause the meter to produce inaccurate
6.1.1.7 Ability to compute one or more of various types of
results. If it is necessary to modify the circuits of an instrument
sound level, that is, the percentile level, (L ) or the time–av-
X
in order to use headphones, it shall be done by, or under
erage sound level (L ) also called equivalent sound level
AT
guidance from, the instrument manufacturer.Athorough func-
(L ) for the measurement period, and
EQ
tional check and calibration shall be performed by qualified
6.1.1.8 Ability to identify the occurrence of sound-level
technicians before using the instrument.
events which exceed some level threshold and provide data on
6.1.6 When there is a likelihood of adverse conditions, an
thetimeanddurationofoccurrence,andsoundlevelduringthe
environmental enclosure capable of protecting the critical
event, including generation of histograms of the number of
components of the measurement instruments (other than the
occurrences, or durations, that sound levels exceed selected
microphone) from physical damage, keeping them dry and at a
thresholds.
temperature within the manufacturer-recommended operating
6.1.2 Outdoor Microphone System (required)—At a
range. (See 6.1.3.2 regarding protection for the microphone.)
minimum, the outdoor microphone system shall consist of the
6.2 Physical Measurements:
following:
6.1.2.1 Microphone and preamplifier recommended by the
6.2.1 Toensureanaccuracyof1dBinvaluesobtainedfrom
manufacturer of the measurement instrument, and compatible calculations that include the results of distance measurements,
with and supporting theANSIType 1 orType 2 requirement of
the accuracy of the distance measurements to be used in
the sound level meter portion of the system. The microphone calculations must be within 5 %.AGlobal Positioning System
shall also meet the measurement plan requirements for fre- (GPS) or any technique that provides this degree of accuracy is
quencyresponse,directionalresponse,andinternalbackground satisfactory. If the data are to be used for modeling, and if the
noise (self noise). studyareaisundulatinginnature,andthevariationinelevation
6.1.2.2 The windscreen recommended by the manufacturer exceeds2mitis recommended that a topographical map be
consulted for estimating elevation of sound sources, potential
may not be adequate in quiet environments with mild wind
conditions. See 5.2.1 and 5.2.2. receptors, and potential acoustical barriers.
6.1.3 The microphone system shall include the following 6.2.2 Direction—A pocket compass should be used for site
features as appropriate for the time duration and conditions layout work and a wind vane capable of measuring wind
expected during the measurement; direction in octants should be used for determination of wind
direction used for site layout work and determination of wind
6.1.3.1 Microphone and preamplifier system that (a) does
not experience a significant sensitivity- or frequency-response direction.
change caused by humidity effects, or (b) can be used with an 6.2.3 Site Map—If it is not included in the measurement
appropriate desiccant system prescribed by the manufacturer,
plan,itisrecommendedthatasitemapbeacquiredorprepared
6.1.3.2 Microphone Rain Shield. prior to starting measurements.
E1503 − 22
6.3 Meteorological Measurements: 7.3 Within one year, or a period specified by the measure-
ment plan, prior to starting the measurements, verify all
6.3.1 It is important to observe and record wind speed,
equipment specifications claimed by the manufacturer using
relative humidity, and temperature for potential effects on the
standards traceable to a recognized standards organization, and
instruments, and these factors plus wind direction for potential
following recommendations of the instrument manufacturer.
effects on sound propagation.
These checks shall include the instrument, microphone and
6.3.2 For certain types of calibrators barometric pressure
preamplifier, and filters (if used).
mustbeobservedatthetimeofcalibration.Insomecasesradio
7.3.1 Thoroughly calibrate the acoustical calibrator follow-
reports of meteorological conditions can be useful; however, it
ing recommendations of the instrument manufacturer, as speci-
is preferable to use available general accuracy meteorological
fied in the preceding paragraph.
instruments to enable the measurement of:
6.3.2.1 Wind speed (5-km/h increments),
7.4 Measure the self-noise of the measurement system,
6.3.2.2 Wind direction to the nearest of the eight common
including the microphone and microphone preamplifier
compass directions,
system, with all connecting cables in the system, before
starting measurements and at least daily, thereafter, until the
6.3.2.3 Relative humidity (in 10 % increments),
measurements are complete, to verify that the self-noise is less
6.3.2.4 Dry bulb temperature (in 2°C increments), and
than the lowest level to be measured.
6.3.2.5 Barometric pressure as specified by the (acoustic)
7.4.1 Measure the self-noise by covering the microphone
calibrator manufacturer if required for the proper use of the
with a suitable acoustic isolator and recording the indicated
calibrator. The absolute pressure is needed, not the pressure
sound level.
corrected to sea level as reported by the weather bureau.
7.4.1.1 To be effective the isolation device used shall
6.4 Photographs—A camera, shall be carried by the mea-
provide isolation at all frequencies of interest. The level
surement team for the purpose of documenting the equipment
reductionineachfractionalbandofinterestshouldbesufficient
setup and surroundings at least once at each measurement
to assure that the instrument noise is at least 10 dB below the
location.
lowest level of interest.
7.4.1.2 If a suitable acoustic isolator is not available, per-
7. Calibration
form the measurement by temporarily replacing the micro-
phone cartridge with a dummy microphone recommended and
7.1 Verifythecalibrationofthesoundlevelmeterportionof
approved by the microphone manufacturer, recording the
the system using a portable acoustical calibrator immediately
before and after each continuous run of the analyzer in a indicated sound level(s). To the indicated sound level(s), add
the typical microphone self-noise values provided by the
manner prescribed by the manufacturer. If measurement data
stored by the analysis system are to be transferred to magnetic manufacturer of the microphone.
7.4.2 When fractional-band measurements are being
media, store and transfer at least one of the periodic calibration
data sets to a calibration file on media separate from data files. performed,checktheself-noiseineachbandatleastweekly,or
at intervals called for in the measurement plan.
In all cases, enter the calibration data in the official hand-
7.4.2.1 It is recognized that obtaining an effective isolation
written field log at the time of calibration. (See 8.5.)
device may be difficult.
7.2 During a series of related measurements, after initial
7.4.3 If it is not possible to demonstrate ability to measure
calibration adjustment, make no further adjustments to the
to the necessary lowest level, either because of an actual
instrument to make the calibration indication agree with the
instrument self-noise, or because of an isolation device having
expected value, unless required by the measurement plan.
sufficient sound level reduction is not available, clearly mark
Instead, use the calibration record to standardize the data
any subsequent data recorded to reflect the fact that actual
during subsequent data reduction and analysis. If the measure-
sound levels may, at times, be lower than those recorded. The
ment plan requires manipulation of the calibration control
cautionary statement shall, if practical, include an estimate of
during the measurement program, maintain a record of cali-
the self-noise, and a statement concerning the effect it would
bration adjustments over the course of the measurement
have, in terms of the difference between the indicated lower
campaign. Record the time(s) at which calibrations were
levels and the actual lower levels.
performed and the instrument calibration indication before and
after each adjustment. If the change in the indication exceeds
8. Procedure
⁄2 dB, mark the data in a way that will call attention to the
8.1 Selecting Measurement Locations and Times—When
change. If the change is 1 dB or greater, investigate the cause
acquiring sound-level data, select locations and times for
of the change and replace suspect components of the system to
measurements consistent with the reason for making the
the extent possible, in an attempt to isolate the problem in a
measurements and the manner in which the results will be
mannerconsistentwiththemeasurementschedule.Discussany
used.
change of 1 dB or greater in the measurement report. It is
strongly recommended that an instrument that shows an 8.2 Location Descriptions—Alocation description prepared
unexplained calibration drift greater than 1.5 dB over 24 h or as part of a measurement plan can be used for this purpose,
less be taken out of service until the cause of the drift can be otherwiseprepareadetailedwrittendescriptionofthelocation.
identified and remedied. Also, verify calibration if the sound Describe the location in terms of its relation to permanent
level meter or microphone is abused (dropped, wet, etc). landmarks. List and give distance and bearing to structures,
E1503 − 22
roads, and other identifiable noise sources that are within 1000 acoustical or electromagnetic interference as well as wind
mof,andvisiblefrom,thesite.Photographsarerecommended, turbulence effects. In this case locate the microphone as far
as are USGS or other satellite imagery, topographic maps, site away from the vehicle as a 30-m microphone cable will allow.
plans, etc. At a minimum, the distance shall be at least 2 ⁄2 times the
largest dimension of the shelter vehicle.
8.3 Preparation of Equipment—Prepare the measurement
8.3.9 Unless specified differently by the measurement plan,
and analysis system according to manufacturer’s instructions.
support the microphone on a sturdy tripod or mast at a height
Preparation shall include the following steps:
between 1.2 m and 1.5 m above the ground. In general, avoid
8.3.1 Check the battery condition before and after a con-
placingthemicrophonetripodonasurfacethatisnottypicalof
tinuous measurement and record the condition on the data
the locale, or in tall grass (in excess of 0.25 m). The
sheet.
microphonelocationandheightaswellasthesurfacecondition
NOTE 1—Make certain that the useful charge is sufficient to complete
in the area of the microphone shall be described on the data
the planned measurement. Consult the manufacturer of the equipment for
sheet and in the report.
information on battery life and the use of auxiliary battery packs.
8.3.10 Following the guidance of the measurement plan or
8.3.2 Verify calibration of the sound measuring equipment
the microphone manufacturer’s recommendation, orient the
in accordance with manufacturer’s instructions.
microphone properly with respect to the source of the sound to
8.3.3 Replace the wind screen(s) and any other items
be measured.
removed for calibration.
8.4 Conducting the Measurement—Having completed the
8.3.4 At least once each day, more often in wet weather and
preparations called for in 8.1 – 8.3, if the analyzer controls
when measurements are continued over more than an 8-h
permit, start the measurement remotely, or set the analyzer to
period, verify that any system which is intended to keep the
start the analysis aftera1or 2-min delay. This will allow time
microphone and preamplifier dry is functioning properly.
for the operator to move away from the microphone and
8.3.5 Select the weighting and filter bandwidths as outlined
complete any noisy operations before the measurement starts.
in the measurement plan. If no guidance is available, it is
If the delay feature is not available, avoid making extraneous
recommended that at least one analysis channel be used for
sound in the vicinity of the microphone after starting the
A-weighted sound level.
measurement.
8.3.6 Set the averaging time and sample rate as called for in
the measurement plan.
8.5 Maintaining a Log—During the measurement make a
8.3.7 Set the measurement duration, dynamic range, and
written record, preferably using a pre-printed data entry form,
maximum range at values appropriate for the measurement
of any necessary data relevant to the specific measurement
situation. Consider the possible occurrence of intrusive sounds
which is not printed by the measurement system or previously
such as vehicles, aircraft, trains, etc, as well as the relative
recorded. Include the following information.
levels of the equipment self-noise and the lowest sound level
8.5.1 Location Information—Abriefdescription(oneortwo
anticipated during the measurement session. The dynamic
hand-written lines will suffice) of the location which will
range of the system may be smaller than the range of sound
positively associate the location with the description prepared
levels encountered. If this is the case it will be necessary to
in accordance with the instructions in 8.2. If a formal sampling
choose to forgo measurements at one extreme of the range.
plan is being followed, use the name or code assigned to the
Include the choice and the rationale in the measurement plan,
location by the plan.
anddocumentinthefieldlog.Includewiththisinformationthe
8.5.2 Thedate,startandendtimeofthemeasurement.Ifthe
manner in which the instrument documents an out-of-range
measurement is not within the time period called for by a
measurement.
predetermined plan, state the reason for the deviation.
8.3.8 Protection of Equipment:
8.5.3 Information sufficient to identify the manufacturer,
8.3.8.1 Provide protection for the analyzer against rain and
model, serial number (where applicable), and the last labora-
solar heating as necessary, especially if measurements will
torycalibration(whereapplicable),forthefollowingacoustical
involve a substantial time period. Consult the manufacturer’s
instrumentation system components, when used:
specifications for acceptable ranges of temperature and
8.5.3.1 Analyzer or sound level meter,
humidity, and take steps to maintain the equipment environ-
8.5.3.2 Microphone,
ment within these ranges, recognizing that solar heating could
8.5.3.3 Outdoor microphone system,
increase equipment temperature above ambient air tempera-
8.5.3.4 Microphone cable, and
ture.
8.5.3.5 Calibrator.
8.3.8.2 Obtain any microphone cable needed to allow
8.5.4 Environmental Conditions—Record environmental
proper placement or sheltering of equipment from the manu-
conditions representative of the measurement set. The infor-
facturer of the equipment, or meet the manufacturer’s specifi-
mation recorded shall include the following:
cations. Tests shall be performed to determine that the cable
8.5.4.1 Temperature,
meets manufacturer’s specifications, and that the microphone
8.5.4.2 Relative humidity,
systemandcableperformsatisfactorilyovertherangeofsound
8.5.4.3 Barometric pressure (and altitude, if required for
level and frequency to be measured.
microphone calibration),
8.3.8.3 If it is necessary to use a vehicle as a shelter for both
the operator and equipment, take extreme care to avoid 8.5.4.4 Wind speed (range if appropriate),
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8.5.4.5 Wind direction (direction blowing from) in octants 9.1.2.5 Analysis system self-noise at the range used.
(N, ENE, . WNW) or multiples of 45° (0, 45, . 315), 9.1.3 Calibration—In addition to a description of the cali-
8.5.4.6 Sky condition, for example, clear, scattered clouds, brationmethod,describeanyproblemswithcalibration,thatis,
partly cloudy, mostly cloudy, overcast, and unusual requirements to readjust system calibration.
9.1.4 Meteorological Conditions—Report meteorological
8.5.4.7 Ground condition, for example, dry, dew, wet, snow.
8.5.4.8 Record the conditions at the beginning and end of conditions for each measurement set. It is recommended that
this data be included in the tables showing the results of the
the sound measurement set, and at least hourly, if the set is
more than one hour in duration. Note the time and type of any measurement sets. If field notes show conditions were stable
throughout several measurement sets, a single statement of the
unusual weather conditions or change. If significant for the
purposeofthemeasurement,measurewinddirectionandspeed conditions will suffice.
9.1.5 Site Descriptions—This may be done by referencing
and record more frequently, for example, at intervals of no
more than 15 min. and including the measurement plan. If there is no measure-
ment plan, a written description shall be prepared, including a
8.5.4.9 If the wind speed is close to the threshold at which
measurements should be suspended, wind speed shall be map showing the microphone location, as well as distance,
direction, and estimated height of structures and vegetation
monitored continuously.
within 100 m of the microphone.
8.5.5 Traffıc Count—Some measurement plans require mak-
9.1.6 Instrumentation Information—Manufacturer, model,
ing a record of traffic count, especially if traffic is the dominant
and, where appropriate, serial number and date of last labora-
source of interest or a significant interference with another
tory calibration for the following:
source of interest. Keep a record according to the instructions
9.1.6.1 Analyzer,
of the measurement plan.
9.1.6.2 Microphone,
8.5.6 Major Sound Sources—Identify major contributing
9.1.6.3 Outdoor microphone system, and
sound sources and record the distance from each source to the
9.1.6.4 Calibrator.
measuring location (see 6.2.1).
9.1.7 Names, business addresses, and phone numbers of the
8.5.7 Comments—Provide brief narrative comments, as
persons making the measurements.
necessary, including:
9.1.8 A statement, to the extent true, that this test method
8.5.7.1 Any unexpected or unusual sound sources which
was followed. Any exceptions shall be noted and reasons
need to be considered in evaluation of the data. Examples in
given.
various situations could be aircraft overflights, railroad
9.1.9 It is recommended that all field notes or log sheets,
operations, barking dogs, or other animal sounds.
whether or not included with the report, be retained for future
8.5.7.2 Unusual weather conditions, especially thunder.
reference.
8.5.7.3 Any pertinent observations such as that acoustical
9.1.10 A brief description of conditions existing at the time
propagation conditions are different from those expected,
of the measurement, relative to past or future long-term
correlation between wind direction and direction of unexpect-
conditions, that is, is this a measurement of the baseline
edly loud or quiet distant sounds, and subjective estimates of
ambient condition, a perturbed condition, or a random sample.
the relative loudness of distance sources compared to nearby
sources. This information can facilitate the evaluation of the
10. Precision and Bias
effect of meteorological conditions on sound propagation.
10.1 The precision of the data obtained using this test
9. Report method is a function of the instrument used, analysis param-
eters selected, and the range of sound levels measured. In
9.1 Report the following information:
general, if the number of samples in a set or subset of data is
9.1.1 All pertinent data prescribed by the measurement plan
at least 10 times the range of the measured data in the set or
and collected during the measurement, including:
subset, the precision for the result of the set or subset will be
9.1.1.1 A tabulation showing the results of each measure-
better than plus or minus 2 dB.
ment set (to the number of decimal places consistent with
requirements of the study and the capability of the measure- NOTE 2—As an illustration, assume an analyzer with a sampling rate of
20samplespersecondperband.Asetofaveragesstoredevery15swould
ment system), with identification of locations, date, time, and
contain 300 samples per average in each band. If the range of the samples
duration of each measurement set.
is not more than 30 dB, each stored average would have a precision of at
9.1.1.2 A description of measured sounds (steady, tonal,
least plus or minus 2 dB because the number of samples is ten times the
impulsive), repetition rate of impulsive sounds, and the iden-
range of the samples.
NOTE3—Thisprecisionappliesonlytothespecificmeasurementperiod
tified or suspected sound sources.
and not to any degree to which that period might be representative of a
9.1.1.3 Adescription of circumstances concerning lost data,
longer period of time.
thatis,interruptedsamples,lossofpower,etc,withanestimate
10.2 Bias is limited to the accuracy of the acoustical
of the effect on data integrity.
instruments.
9.1.2 Information on analyzer settings:
9.1.2.1 Range,
11. Keywords
9.1.2.2 Analysis bandwidths and weightings,
9.1.2.3 Sampling rate,
11.1 acoustical environment; analysis; calibration; commu-
9.1.2.4 Detector response time or averaging time, and nity noise; data storage; digital; equipment; interferences;
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loudness; measurement; measurement plan; meteorological
effects; microphone system; outdoor; precautions; procedures;
sound level; statistics; supporting data
APPENDIX
X1. PREPARING A MEASUREMENT PLAN FOR CONDUCTING OUTDOOR SOUND MEASUREMENTS
X1.1 Scope X1.3.1.3 Type of Analysis Required—The type of analysis
planned for the data obtained.
X1.1.1 This appendix addresses the preparation of a mea-
surement plan to document outdoor sound levels. A detailed
X1.3.2 General Location—Describe the geographic loca-
plan is useful for major environmental noise studies requiring tion of the measurements, for example, the area or political
numerous measurements at several locations over a long
subdivisionthatencompassesallofthemeasurementlocations.
period. This Appendix is intended primarily for use in such Examples of the location would be a specific named subdivi-
cases. However, even simple measurements can benefit from a
sion or platted area, a city, township, county, or state.
brief, generic plan.
X1.3.2.1 Map of the study area—Measurement locations
should be identified on the map by appropriate code numbers
X1.1.2 On occasion, a need to depart from the normal
or letters.
measurement methodology may arise, in order to accommo-
X1.3.2.2 Aerial Photograph—An aerial photograph, at the
date a special situation or a regulatory requirement. This
same scale as the map of the study area, may be useful to
Appendix provides options that are technically correct for
provide added detail of the site
specific situations and provides the information needed for
selecting options.
X1.3.3 Property Owners—Give the names and addresses of
persons or organizations controlling access to property on
X1.1.3 Measurements that may be planned using this ap-
which measurements are to be made. Procedures for commu-
pendix include, but are not limited, to the following:
nicating with property owners should be communicated sepa-
X1.1.3.1 Measurement of low-frequency sound (infra-
rately from the plan.
sound)isincludedbecauseitcancausestructuralvibrationthat
translates to audible interior sound.
X1.3.4 Regulatory Information—If the measurement is re-
X1.1.3.2 Measurement of impulsive sound.
quired by, or results of the measurements will be reviewed by,
X1.1.3.3 Measurements of sound with significant tonal
a regulatory agency, include regulatory information.
content.
X1.3.5 Non-Regulatory Information—There may be occa-
sion where non-regulatory information is considered in the
X1.2 Significance and Use
study. For example, criteria may be established by the project
X1.2.1 This appendix has been prepared to provide both an
which are more restrictive than regulatory limits. Any such
outline for a measurement plan and guidance in selecting
criteria should be noted.
procedures that are appropriate for the type and purpose of the
measurements to be performed. Use of the guidelines provided
X1.3.6 Time Period Covered—Describe the time period
willproducemeasurementresultsthatarereproducibleandcan over which the measurements are to be made. Include any
be documented, that are consistent with requirements of specificrequirementstodocumentsoundlevelsassociatedwith
government and industry, and that can be validated using specific activities in progress, or when certain atmospheric
information gathered and documented in the course of the conditions prevail.
measurement program.
X1.3.7 Selection of Measurement Locations—This section
X1.2.2 This appendix outlines procedures for making and
provides the measurement locations to be used. If the measure-
documentingthephysicalobservationsnecessarytoqualifythe ments are to be used to characterize the acoustic environment
measurements.
of a point, zone, district, or enclave, the measurements loca-
tions must be validated in a manner that ensures a degree of
X1.3 Recommended Report Format
spatialresolutionnecessarytoadequately,andappropriatelydo
X1.3.1 Scope of Measurement—A clear statement of the this. (See also ANSI S12.9, Parts 2 and 3.)
scope to provide an appropriate opening statement for the
X1.3.8 Instrumentation—Provide a description of all mea-
measurement plan. The following basic information should be
surement equipment u
...