Noise

Measurement
Manual

For use in testing for

compliance with the
Environmental Protection
Act 1994

Third edition 1 March 2000

 Contents
Part A General
1 Introduction
1.1 Purpose
1.2 Use
1.3 Limitations

2 Status and scope

2.1 Contents of manual
2.2 Responsibilities of ‘authorised persons’
2.3 Edition identification

Part B Preparation
3 Planning for noise measurement
3.1 Determine the purpose
3.1.1 Why measure noise?
3.1.2 Programmed noise assessment
versus incident investigation
3.1.3 Measurement details:
Where, when, what characteristics?

4 Equipment
4.1 Sound level meters
4.2 Sound level calibrators
4.3 Octave and one-third octave measuring equipment
4.4 Level recorders
4.5 Tape recorders
4.6 General caution

5 Personal safety
5.1 General
5.2 Personal protective equipment (PPE)
5.2.1 Intent of PPE
5.2.2 PPE available
5.2.3 Description of PPE

Part C Measuring noise

6 Pre-field checks
7 Making noise measurements
7.1 Site instructions
7.2 Measurement techniques
7.3 Use of instruments
7.4 Measurement positions
7.4.1 Outdoor measurements
7.4.2 Remote points
7.4.3 Indoor measurements
7.5 Measurement time and interval
7.6 Atmospheric conditions
7.7 Background sound pressure level
7.7.1 Simple situations
7.7.2 Complex situations
7.7.3 Indoor measurements
7.8 Adjusted maximum sound pressure level
© The State of Queensland.
Environmental Protection Agency, 2000. 8 Reporting results
8.1 Keeping records of field measurements
Copyright protects this publication. Except for purposes permitted
by the Copyright Act, reproduction by whatever means is prohibited
8.2 Atypical or non-complying results
without prior written permission from the Chief Executive Officer of 8.3 Importance of general observations
the Environmental Protection Agency. Enquiries should be 8.4 Equipment problems
addressed to: Chief Executive Officer, Environmental Protection
Agency, PO Box 155 BRISBANE ALBERT STREET QLD 4002.

Noise Measurement Manual 3rd Edition, 1 March, 2000

Produced by the Queensland Environmental Protection Agency.
Appendixes
MU43 — 1 March,1995 A Australian Standards
MU57 Revised — 1 March, 2000

Recycled paper saves energy and resources B Noise measurement form

Noise Measurement Manual • 3rd edition • 1 March 2000 • ISBN 0 7242 6411 6 1
Part A General 2 Status and scope
2.1 What this manual contains
1 Introduction This manual explains how to:
• plan a noise measurement;
1.1 Purpose • take on-site measurements; and
This manual tells ‘authorised persons’ as defined in the • report noise measurements.
Environmental Protection Act 1994 how to measure
environmental noise to a standard suitable for determining Content has been prepared based on Australian Standards.
compliance with the Act, its subordinate legislation, and Part B of the manual describes the preparations needed
legal instruments issued under the authority of the before undertaking noise measurements. Part C explains
legislation. the procedures to be followed when measuring noise.

It also aims to inform people other than ‘authorised persons’ 2.2 Responsibilities of
about measuring environmental noise.
‘authorised persons’
1.2 Use All ‘authorised persons’ as defined in the Environmental
This manual is for use by: Protection Act 1994 who take noise measurements are
• ‘authorised persons’ appointed under the Queensland responsible for performing their work in accordance with the
Environmental Protection Act 1994; procedures described in this manual. They must be able to
• anyone needing to know about measuring environmental prove that they did not deviate from the procedures except
noise, particularly with regard to checking compliance with in special circumstances.
statutory requirements; and
• licence holders and other authorities (and their As soon as possible after finishing noise measurements,
consultants) under the Environmental Protection Act officers should record in an official notebook whether or not
1994. the measurement followed specified procedures.

Officers must also provide details of any deviations from the

1.3 Limitations procedures, and the special circumstances which led to
This manual cannot cover all circumstances that could be those deviations.
encountered when measuring and assessing environmental
noise. 2.3 Edition identification
In cases where the manual does not give sufficient or This current edition is the third edition of the noise manual,
relevant directions, consult a relevant Australian Standard and is dated 1 March, 2000. Future editions will be
listed in Appendix A. numbered sequentially — 4th edition, 5th edition, and so on.
Each page of the manual has the publication title,
identification number and date of publication.

Copies can be bought from:

Naturally Queensland Information Centre Environmental
Protection Agency
Ground floor
160 Ann Street, Brisbane, QLD, 4000
PO Box 155
BRISBANE ALBERT STREET, QLD, 4002.
(07) 3227 8185, fax (07) 3227 8749.

2 Noise Measurement Manual • 3rd edition • 1 March 2000 • ISBN 0 7242 6411 6
Part B Preparation 4.2 Sound level calibrators
An acoustic calibrator compatible with the SLM is required
3 Planning for noise for regular field calibration. The calibrator should conform to
measurement IEC942-1988 Sound Calibrators. In addition, the calibrator
should be recalibrated at least once each year in a NATA
This section lists steps to be taken in planning noise registered laboratory.
measurements.
4.3 Octave and one-third octave
3.1 Determine the purpose measuring equipment
3.1.1 Why measure noise? Filters should conform to the requirements of Australian
Noise is measured to assess compliance with a statutory Standard AS/NZS 4476:1997 Acoustics — Octave-band and
provision, such as a condition attached to a licence, or to fractional-octave-band-filters.
investigate a noise complaint.
4.4 Level recorders
3.1.2 Programmed noise assessment
Graphic level recorders (or chart recorders) can be
versus incident investigation connected to most SLMs and are used to provide a hard
Noise assessment falls into two groups, depending on the copy (or graph) of time varying noise being measured by the
time available to plan the work. These are: SLM.
1. assessments made as part of a planned program for
checking compliance, when officers have ample time The graphic level recorder can be used to provide a hard
(days or weeks) to plan ahead; and copy of the respective frequency analysis. In this respect,
2. assessments made in response to reported or observed special frequency analysis chart paper can be used on the
incidents of environmental nuisance. In these cases, it level recorder.
may not be possible to plan ahead, and decisions may
have to be made quickly. Electronic graphic level recorders may also be used.

3.1.3 Measurement details: where, when, 4.5 Tape recorders

what characteristics? When additional analysis equipment such as frequency
When assessing noise emitted by an organisation holding a analysers, level recorders, and statistical analysis
licence or notice (or similar legal instrument), the purpose of instrumentation is not available in the field, a tape recording
the assessment is usually to check whether or not the is a convenient way of recording the particular noise source
emission complies with the conditions imposed in the licence. in question for later analysis.
In such cases officers should refer to the current conditions Tape recorders should meet the requirements of Australian
and note the specific details. These include: Standard AS2680-1984 Acoustics — Performance for tape
recording equipment for use in acoustical measurement
• Assessment locations systems.
Most licences have conditions specifying where
measurements are to be taken. Some licences have more For those situations where band pass filters cannot be used
than one measurement point. Where no measurement to assess the predominant frequency components of a noise
location is specified, officers should select a suitable location. source (all cases except for steady noise having fluctuations
less than ±4dB(A)), a good quality tape recorder is required.
• Times of emission
Some conditions specify that noise emissions are permitted A tape recording can also be used on occasions to confirm
only at certain times of the day. subjective adjustments made to measured levels where
dominant tonal sounds are perceived in the overall noise.
• Noise limits
Licence conditions will usually specify the permitted noise
levels for certain periods of the day. 4.6 General caution
Devices such as tape recorders, level recorders and
statistical analysers may be included in the measurement
chain provided that the inclusion of such devices does not
4 Equipment significantly degrade the performance of the overall
measurement chain.
4.1 Sound level meters
This implies that measurement accuracy should not be
A portable sound level meter (SLM) meeting the degraded below that which would be obtained by using an
requirements of Australian Standard AS1259-1990, SLM designed to meet AS1259 -1990, Type 1 or Type 2.
Acoustics — Sound Level Meters Part 1: Non-integrating or
Part 2: Integrating-averaging, and of Type 1 (precision) or
Type 2 (general purpose) should be used.

Equivalent international standards such as IEC651 and

IEC804 are also appropriate. Statistical SLMs are widely
used to automatically acquire statistical noise data.

The SLM should be set on frequency-weighting ‘A’ and time-

weighting ‘F’ for normal measurement purposes. For quality
assurance purposes, the SLM and the microphone should
be recalibrated as a set at least once every two years at a
calibration laboratory registered by the National Association
of Testing Authorities of Australia (NATA).
Noise Measurement Manual • 3rd edition • 1 March 2000 • ISBN 0 7242 6411 6 3
5 Personal safety For protection against UV radiation, the following are
available:
Personal safety comes first. • a wide-brimmed sun hat to protect the head, tips of ears
and neck during most activities; and
No task is so important that safety • sunscreen cream (rating SPF15+) to be applied to the
can be compromised. back of the neck and to the face if wearing a safety
helmet. Helmets allow more of the face to be exposed to
5.1 General the sun than a wide-brimmed sun hat.
Noise measurement in the field is not regarded as a Hand protection
hazardous activity. However, some general precautions Hazards to hands include solar UV radiation and
should be taken to ensure against risks such as: physical injury. Protection against sunlight is described
• drowning; above.
• injury;
• contracting water-borne diseases; and Foot protection
• loss of equipment. If walking in any industrial premises where heavy equipment
is located, or heavy loads are transported, officers should
Before setting up equipment to make noise wear normal safety footwear. This comprises safety boots
measurements, officers should assess potential hazards with steel toe cap and instep protection.
and decide on appropriate ways to deal with them. This is
best done by a risk assessment. A procedure for risk Hearing protection
assessment is given below. In some circumstances, it may Ear muffs or ear plugs are used for this purpose. Officers
be better not to take a particular risk. should wear these whenever entering a signed ‘hearing
protection’ area, or whenever it is considered that noise
5.2 Personal protective levels are liable to cause discomfort.
equipment (PPE)
PPE provides a physical barrier, designed to prevent
contact between a person’s body and a hazardous object,
substance or radiation.
Note: Any person who has not received adequate
training in the use, fitting and maintenance of PPE
should not be involved in noise measurement.

5.2.1 Intent of PPE

The role of PPE is to act as a front-line defence for the body
against injury and invasion by disease precursors or
organisms. It is NOT meant to replace ordinary care aimed
at minimising such contact.

Further information on PPE is available in the Division of

Workplace Health and Safety Code of Practice on Selection,
Provision and Use of Personal Protective Equipment.

5.2.2 PPE available

The PPE normally supplied to Department officers is listed
in table 5.1, plus some other items available. The equipment
is described later in this section.

The items should be worn correctly, maintained and where

necessary, serviced. Some items have use-by dates and
particular storage requirements. Take care to follow these
directions, especially for filter masks and cartridges.

5.2.3 Description of PPE

The types of PPE needed will depend on the hazards likely
to be encountered. Officers need to know what these
hazards are to choose the appropriate protection. PPE is
described here in relation to particular hazards.

Protection for skin in general

Hazards to be protected against include solar UV radiation
and exposure to aerosol mists. Noise measurements should
not be made in areas exposed to aerosol mists.

Officers should protect skin exposed to the sun by applying

sunscreen cream (rating SPF15+). Areas particularly at risk
include the back of neck, backs of hands and backs of knees.

Head protection
Hazards include being struck by falling objects and effects
of solar UV radiation. For protection against falling objects,
officers need a safety helmet. Officers must wear this in
designated ‘hard hat’ areas, and any other places where
officers believe head protection is needed.
4 Noise Measurement Manual • 3rd edition • 1 March 2000 • ISBN 0 7242 6411 6
 A procedure for risk assessment
Step 1: Identify the hazards (source of injury or disease). • electricity — shocks, burns;
• vibration — effects on hands; and
Step 2: Analyse the consequences (potential injury or • any other known hazards.
disease).
Where risks of injury or disease are identified, officers
Step 3: Estimate the risk (frequency, duration and should do whatever is appropriate to control the risks.
outcome of the consequences). Examples of how to do this include:
• replacing a procedure or material with a less
Step 4: Determine what action to take (evaluate methods hazardous one;
of removing, reducing or controlling the risk). • re-designing work processes, work methods or
equipment;
In making this assessment, consider the following • isolating hazards from the workers (and from those
hazards, or any other potential hazards applicable to a not involved in the work) for example by enclosures
situation: or guards; and
• gravity — falling objects, people falling; • adjusting the duration or the conditions of exposure
• kinetic energy — projectiles, penetrating objects; to the risk.
• mechanical energy — caught between, struck by, struck
against; Only where these methods are not practicable or not
• hazardous substances — skin contact, inhalation; sufficient should personal protective equipment (PPE) be
• thermal energy — spills and splashes of hot matter; considered the appropriate protection against risk of
• extremes of temperature — effects of heat and cold; disease or injury.
• radiation — ultraviolet, arc flashes, microwaves, lasers;
• sound — hearing damage; If PPE is to be used, care should be taken in deciding on the
• biological hazards — pathogenic micro-organisms; particular items of equipment and how they are to be used.

Noise Measurement Manual • 3rd edition • 1 March 2000 • ISBN 0 7242 6411 6 5
Part C Measuring noise 7.2 Measurement techniques
Select an instrument location. This choice will depend on
the type of measurement conducted. Preferably,
6 Pre-field checks instrumentation should be located so that direct reading
Certain checks should be made before field measurements from the SLM display is possible. Several measurement
are obtained. These checks include: techniques are described below.
• placing any instruments using storage batteries on charge;
• checking the calibration status of instruments from copies Hand-held, quick assessment, microphone not remote:
of calibration certificates or labels on instruments; This type of assessment would normally be conducted
• inspecting instruments for physical damage, particularly before planning a full noise investigation and generally will
the thread, diaphragm and protective grid of the be limited to a few minutes. Good measurement practice
microphone; (Caution: Do not remove the protective grid requires that the SLM is held at arm’s length.
of the microphone and never touch the diaphragm.)
• connecting all equipment in a bench-top simulation and SLM mounted, microphone not remote: This technique
including any extension cables to be used; might be used when a level recorder is not available. It
• checking and adjusting (if necessary) the mechanical zero allows ‘hands free’ recording of noise levels while fulfilling
of analogue instruments; the requirements of directly observing the instrument and
• selecting the appropriate polarisation voltage setting (if maintaining the minimum required distance from the
necessary) on the SLM to suit the microphone; microphone.
• switching the equipment on and running a full electrical
and acoustical check using the calibrator; (Caution: The disadvantage of this technique is that noise from
Ensure that power to the SLM is switched off before fitting manipulation of instrument controls, as well as noise from
the microphone.) the operator, might be detected as sound by the meter and
• checking the battery condition of the SLM and the could influence results.
calibrator;
• placing the microphone protection cap (if available)on the Microphone remote from SLM : This technique enables
microphone; and the operator to be close to the SLM without disturbing the
• storing the SLM with no loose equipment in its carrying sound field at the microphone position. Meter detection of
case if one is available. noise from instrument manipulation or operation, or from the
operator can be minimised.
The equipment is expensive and sensitive and must be
treated accordingly. In-transit instructions include: In addition, the operator can adopt a more comfortable
• protecting equipment from unnecessary shock and position for extensive measurements. This arrangement is
vibration; achieved by using the extension cables (preferably the
• protecting equipment from extremes of heat (never leave instrument manufacturer’s recommended cables) which are
equipment in a locked vehicle for any length of time during available in several lengths.
hot periods); and
• protecting equipment from moisture/condensation. Adaptors and cables for microphone extension should
preferably conform with the instrument manufacturer’s
published interconnection recommendations.

7 Making noise measurements Level recorder: When a level or chart recorder is used in
conjunction with an SLM, the interconnecting cable between
7.1 Site instructions the instruments should be the equivalent of the cable
supplied by the manufacturer.
Choose measurement positions taking into account:
• the weather and other site considerations such as rain, The length of the cable is not critical, but is usually
wind noise and insect noise; standardised. A remote microphone should routinely be
• the location and direction of any noise source/s; used in conjunction with a level recorder so that noise from
• the most sensitive position at the affected premises where level recorder operation is not detected by the SLM. This
maximum noise levels are expected; configuration allows direct notation of the level recording
• the need to avoid reflecting surfaces (where possible); with levels observed on the SLM.
and
• the need to avoid atypical barriers (elevate microphone if If one of the longer connecting cables between the SLM and
appropriate). the level recorder is used, the instruments should be located
adjacently so:
Sketch measurement position(s) on the standard noise • warnings of overload can be observed;
measurement form and include: • battery condition can be observed, which will assist in
• living areas identified as likely to be particularly affected preventing the loss of readings due to battery failure; and
by the source noise; • the ‘pause’ function (if fitted) of the SLM can be accessed
• noise sensitive areas of premises; to assist in excluding unwanted noise.
• noise source(s) direction and approximate distances;
• relevant barriers, mounds, vegetation and ground cover in
Caution: When using a remote microphone, give close
the separation zone;
attention to a subjective comparison between the levels of
• wind direction and speed; measured noise and audible noise. If the two do not appear
• location of measurement position(s) indicating distances comparable, an unrelated noise (such as that from a cricket
from fixed reference points which are unlikely to change; or bird) might have sounded close to the microphone.
and Relocating the microphone or some other action is required.
• identification of other land uses in the vicinity of the
affected premises.
7.3 Use of instruments
Set up the instrumentation at the appropriate location and
allow it to stabilise to existing atmospheric conditions. Set or
check the status of all function settings.
6 Noise Measurement Manual • 3rd edition • 1 March 2000 • ISBN 0 7242 6411 6
• Check the calibration of the SLM and adjust if necessary. Outdoor noise levels should normally be measured 1.2m–
Compensate for the use of any extension cable by 1.5m above ground level or, in the case of elevated
calibrating the SLM with the extension cable connected. microphones, at the centre of windows.
Calibration must be carried out at regular intervals if
extensive measurements are made, or if a tape recorder Note: Microphones could need to be higher than 1.2m–1.5m
is moved, affecting the settings. above ground level in certain situations. The principle to be
• Calibrate/adjust any level recorder that is to be used. (The applied when determining if the microphone height needs to
range control (if fitted) of the SLM may be used to check be increased is whether the sound pressure level of the noise
that the SLM and level recorder readings agree.) can be accurately represented at 1.2m–1.5m above ground.
• Adjust the tape recorder for optimum recording.
• Observe the periodicity of the noise and reset the time Situations where measurement at 1.2m–1.5m above ground
function (if available) where necessary. level may not give accurate or complete determination of the
• Fit the windscreen. sound pressure level include the following:
• Adjust the full scale deflection (FSD) on the SLM to get • low-set residences where a high boundary fence is close
the best signal/noise ratio (S/N) without overload. to the affected residence, (i.e. several metres away), and
• Annotate any level recording with: is providing a shield for a noise source(s), and is in turn
- the new FSD and confirm that the SLM and the level generating a semi-reverberant sound field at low heights;
recorder readings agree; and
- the test reference; and • high-set residences.
- the time and the date.
• Press the pause and reset controls (if incorporated in the In these situations, measurements might need to be
SLM) to begin sampling. conducted at 1.2m–1.5m above ground level as well as at
• Mark the beginning and end of all sample periods on any elevated microphone heights to ensure an accurate and
level recording together with timing marks at regular representative determination of the adjusted average
intervals. maximum sound pressure level is made.
• Accurately mark and identify all the noise levels registered
on the level recorder which are caused by noise from the Situations might also arise where high boundary fences act
source or premises of interest and which are unaffected as shields in the path of the intrusive noise from the source
by extraneous noise. Other sources contributing to the to the residence, and where the residence is well separated
ambient noise at the measurement position may be from the boundary fence, such as when the fence is along
marked and identified for reporting later. the rear boundary. In these situations, measurement
• If an electronic event recorder is used, record each event position(s) should be selected with a view to ensuring the
by hour, minute and second, such as 10:35:35, for principle of accurately and completely determining the
subsequent analysis. sound pressure level is followed.
• Recheck the calibration of the SLM or the whole system
(where a level recorder or tape recorder is used) at the If people affected are unlikely to be normally exposed to
end of the measurements. Where the SLM registers a noise where maximum levels are expected, alternative
discrepancy of greater than 1dB between checks, points within the apparent boundaries of affected areas or
measurements might be considered invalid. premises can be used.

Note: Irrespective of the field operation instructions described 7.4.2 Remote points
above, in all cases reference should be made to the instruction
manual for the appropriate instrument (SLM, band pass filter, level
Measurement points closer to noise sources, or within or
recorder, or tape recorder). outside commercial or industrial premises and providing the
worst-case noise situation, might be selected to assist
assessment by:
• avoiding contributions from other sources;
• reducing atmospheric influences on noise propagation; or
7.4 Measurement positions • ensuring ready access to measurement points not
7.4.1 Outdoor measurements associated with affected premises.
Normally, measuring positions should be selected
outdoors where representative maximum adjusted noise 7.4.3 Indoor measurements
levels are expected or indicated by complainants. The Noise should be measured indoors only when:
position(s) should be located: • representative outdoor measurements cannot be made
• within the apparent boundaries of land: even by supporting the microphone outside windows of
- at or near the boundary; habitable rooms; or
- within 20m during the day and evening period, and • special investigations are needed to resolve complaints.
3.5m during the night period, of buildings normally used One typical example occurs with low frequency noise
for human habitation (not hotels, motels and similar); intrusion where the noise level does not exceed a dB(A)
- within 3.5m of the external walls of educational limit but is still annoying. In such cases, special
buildings, the wards or bedrooms of hospitals, hotels, investigation by acoustical consultants is preferred.
motels and similar. The time periods commonly used for
noise measurement purposes are: Measurements should be made in habitable rooms with
day: 7am–6pm doors and windows open or closed to represent typical
evening: 6pm–10pm ‘worst case’ conditions. Measurements should be made at
night: 10pm–7am least 1m from walls, and from 1.2m–1.5m above the floor,
• within the apparent boundaries of areas where motor and at least 1.5m from the window(s).
vehicles or vessels are normally used for human
habitation, such as caravan parks, residential marinas or Measurements should be made as close as practicable to
designated moorings; times when the greatest subjective intrusion is likely. The
• at noise-sensitive locations on the boundaries of time interval for measurement, T, should be long enough to
established commercial or industrial premises; and ensure that recorded data provide a representative
• within the apparent boundaries of passive recreation description of measured noise.
areas, such as picnic grounds, public gardens and parks,
or special protection areas such as national parks,
environmental parks, and archaeological sites.
Noise Measurement Manual • 3rd edition • 1 March 2000 • ISBN 0 7242 6411 6 7
7.6 Atmospheric conditions Noise levels contributing to L Abg,T or L A90,T should exclude
noise from close traffic, birds, insects, animals and other
Noise should be measured during fine weather conditions similar noises, unless such noise is a normal or seasonal
with calm to light winds (0–10km/h). A wind direction feature of the location which cannot be practically avoided. All
favouring noise propagation from source(s) to receiver(s) noise levels should be written down and kept as a record.
should be chosen if this is a true representation of the
normal situation. Different conditions and their effects on Note: In relatively quiet areas, insect noise might tend to dominate
measurements should be noted. background noise levels for large parts of the year, particularly
during the warmer months. Lower ambient and background noise
levels might generally be recorded during the winter months when
7.7 Background sound pressure insect activity is absent or at low levels. Careful consideration
level should be given to measurements of background noise levels in
such instances.
Background sound pressure level L A90,T is the A-weighted
sound pressure level obtained using time-weighting ‘F’ The principle that the background noise level should be the
exceeded for 90 percent of the measuring period ‘T’. ‘average of the levels during the quiet periods’ should be
kept in mind. Local knowledge of the area and the influence
The acceptable equivalent of L A90,T is L Abg,T, the A-weighted of insect noise on background noise levels might be very
sound pressure level obtained using time-weighting ‘F’ and important in making a determination of the background
arithmetically averaging the lowest levels of the ambient noise level.
sound pressure level during time interval ‘T’.
Background noise levels should include constant
The background sound pressure level is commonly denoted noise from identifiable human activity or distant machine
as background noise level and background level. sources clearly audible at the measuring point if such noise
is a normal feature of the location which cannot be
Obtaining an accurate background sound pressure level is practically avoided.
important as it may be one of a number of criteria used to
consider whether a noise from a source is reasonable. It L A90,T and L Abg,T are corrected for reflections by subtracting
may also form the basis of a reduction in noise emission 2.5dB(A) when measuring points are outdoors and microphones
levels to an acceptable level. are located 1m–2m from acoustically reflecting surfaces.
Complete and accurate determination of the background Background noise levels should be measured as close as
sound pressure level should be considered as an element in a practicable to the time(s) of day when the intrusive noise is
successful environmental noise investigation. It can be used alleged to be excessive, and in period(s) during which the
as the basis for the noise level limit set for noise from the alleged excessive noise is absent.
source premises and therefore can be the basis for requiring
a reduction of noise emissions to acceptable levels.
7.7.1 Simple situations
When possible, the same measuring points selected for In simple situations, background levels should be measured
source noise measurement should be used. Remote points and noted immediately before and after measuring the level
should not be used to obtain background noise levels for of noise from the source. The background level should then
determining limits. be based on the averaged figure obtained on these two
occasions.
Background noise measurements should be made at
preferred locations in the absence of the noise being AS1055-1997 suggests a minimum 10 minute to a
investigated. maximum one hour period for assessing background noise,
although 15 minutes is the commonly accepted period. The
If measurements cannot be made at an assessing officer should decide the appropriate
affected place because of other dominant noise sources, measurement period.
measurements are to be made instead at similar locations
chosen very carefully to ensure equivalent background Reasons for a longer assessment time include transient
levels caused by traffic flow or general industrial activity. noise during the survey period lasting long enough to
Local knowledge of the area might be necessary to make seriously affect the LA90. In these cases, it may be more
appropriate selections. appropriate to move to a remote measuring location that is
not affected by extraneous noise.
Background noise levels should be measured during fine
conditions with calm to light winds (0–10km/h). Different 7.7.2 Complex situations
conditions and their effects on measurements should be In complex situations, multiple measurements of
noted. background noise levels might be needed over various
times of the day, or several days or months, to ensure that a
Where the background noise level does not fluctuate by complete and accurate determination of background noise
more than 5dB(A) with analogue meters, L Abg is considered levels is made.
equivalent to the visual average of the minimum levels
recorded on an SLM. For example, complex situations could include those where
source premises and affected premises are well removed
If the variation is greater than 5dB(A), L Abg should be determined from each other (ie. several hundred metres apart), or
using an SLM and a level recorder or tape recorder. where atmospheric conditions or operating conditions
change significantly during the year or over time.
For digital SLMs, the L A90,T parameter should be read and
recorded using the A-weighted sound pressure level 7.7.3 Indoor measurements
obtained using time-weighting ‘F’ exceeded for 90 percent of With indoor measurements, the background level is
the measuring period ‘T’. measured indoors at the same location used to determine
the source noise level. Conclusions on a representative
For L A90,T or L Abg,T , a complete subjective report on noise background level are based on a careful and documented
sources contributing to background during measurement assessment of data collected during site visits. Unattended
periods is required. monitoring data should be used only to verify conclusions.
8 Noise Measurement Manual • 3rd edition • 1 March 2000 • ISBN 0 7242 6411 6
Source noise levels and background noise levels should be For noise of a steady and continuous nature such as that
rounded to the nearest dB(A) as follows: from fans and compressors, an interval of five minutes may
• less than or equal to 0.5 — round down; and be appropriate if this period includes at least one typical
• greater than 0.5 — round up. cycle of operation (if any).

7.8 Adjusted maximum sound The maximum operating level due to cycling of refrigeration
units or the on-load condition for compressors should be
pressure level used to obtain the L Amax,T level.
A descriptor adopted for general noise measurement is
LAmax,T which is the A-weighted sound pressure level 7.9 Other measurement
obtained by using time-weighting ‘F’ and arithmetically
averaging the maximum levels of the noise under procedures
investigation, unaffected by extraneous noise, during time Sound can be measured using other measurement
interval ‘T’. procedures as detailed in as AS1055-1997, the
Environmental Protection (Noise) Policy 1997 and the Policy
Extraneous noise means all noise not emitted from the Users’ Guide.
source(s) or premises of concern and includes such things
as noise from passing traffic, seasonal insects and barking
dogs, unless such noise can legitimately be defined as part
of the noise under investigation.

The term sound pressure level is commonly denoted as

noise level.

L Amax,adj,T is obtained by making adjustments for tonality and

impulsiveness as specified in AS1055-1997 in relation to
LA%, adj, T, the adjusted percent exceedance A-weighted
sound pressure level. If tonality due to, for example, the
humming of cooling fans or impulsiveness from hammering
is detectable, then an adjustment can be added to LAmax,T.

If tonality or impulsiveness is a characteristic of the sound

being measured, then an adjustment can be added for each
characteristic detected.

The noise from individual sources associated with premises

having multiple noise sources such as an extractive
industry might need to be averaged separately. Levels
contributing to L Amax,T should be written down and kept as a
record. The absolute maximum instantaneous level, Max L
pA, measured during time interval ‘T’ should be reported.

For SLMs having facilities for statistical analysis, a

simultaneous measurement of noise exceedance levels (L
A%, T) should be carried out and data reported in the noise
measurement form.

Average maximum sound pressure levels L Amax,T are

corrected for reflections by subtracting 2.5dB(A) from the
derived value when the measuring points are outdoors and
microphones are located 1m–2m from acoustically reflecting
surfaces.

When measurements are conducted in the plane of the

reflecting surface, such as with a microphone at an open
window, no corrections should be made.

For more complex situations where dominant tonal

components are detectable, a procedure for determining
tonal adjustment is specified in AS1055-1997 Appendix B
requiring one-third octave band frequency analysis.

Due to the complexity of this procedure, it should be restricted

to supporting subjective evaluation when dispute is likely.

The noise level of the alleged excessive noise will be

measured at the chosen measurement point and as close
as possible to the time of day when the noise is alleged to
be excessive. The time interval for measurement, T, should
be long enough to ensure that recorded data provide
representative descriptions of measured noise.

A time interval of 15 minutes might be appropriate for noise

sources having variable noise levels from multiple sources,
such as extractive industry.
Noise Measurement Manual • 3rd edition • 1 March 2000 • ISBN 0 7242 6411 6 9
8 Reporting results 2. Instrumentation
For all items of equipment used for the measurements,
Information in this section is intended to help officers make including calibration equipment, the following information
noise measurements in a scientifically valid manner, should be recorded:
ensuring results represent the field conditions fairly. • name;
• manufacturer;
• type;
8.1 Keeping records of field • serial number(s) (also of microphones, if removable); and
measurements • date of most recent laboratory calibration.
Because the results of field measurements might be used in
3. Acoustic data
court actions, officers must carry out all measurement
The report should include the following, as appropriate:
procedures in a precise, consistent and reliable manner.
• location(s) of the measurement position(s), and
microphone orientations;
The original records made during measurements • type of noise being measured;
could be required in court. Therefore, these records should • character of the noise, such as steady, intermittent,
be made in an Official notebook and treated with care. impulsive of the sound field, and associated observations
Hand-writing needs to be clear and unambiguous. such as vibrations and amplitude or frequency
modulation;
8.2 Atypical or non-complying • noise levels measured;
• frequency weighting used for each measurement;
results • time-weighting characteristic for each measurement;
If results appear atypical or non-complying, it will be • duration of each measurement period;
necessary to repeat the measurements. • for source measurements, background noise level with
the source not in operation if possible;
• date and time when each measurement was performed
8.3 Importance of general (include justification of measurement period);
observations • tonality adjustment;
• impulsiveness adjustment; and
Observations made during measurements can be • any other data considered appropriate.
extremely important in assessing atypical events or long-
term trends, especially when investigating incidents of In addition, the following qualitative information could be
environmental nuisance. included to help interpret the results:
• the possibility of locating the origin of the noise;
Records should be made of audio conditions using tape • the possibility of identifying the sound source;
recordings and visible conditions with photographs as these • the nature of the sound source such as industrial plant or
might be difficult to describe accurately in words. Tape and air-conditioner;
photograph numbers should be recorded to avoid any later • the character of the sound such as broad-band, impulsive,
confusion. or tonal;
• the connotation of the sound such as inappropriateness in
Note: For 35mm or similar rollfilms, the frame number on the the neighbourhood and information content; and
film might be one or two numbers different from the film • other noise source(s) apparent at the time of
counter number, depending on the exact positioning of the measurement.
film on the takeup spool when loading and the number of
frames wound on before closing the camera back. Officers
need to be aware of this when comparing photograph
numbers recorded with the numbers along the edge of the
negative strip. The printed photograph should be matched
against the negative.

8.4 Equipment problems

If any of the apparatus required to take measurements is not
in good order and condition and cannot be rectified with
confidence, it is usually better not to collect data. Faulty
equipment should be returned to the office for assessment
and to the supplier or manufacturer for repair.

The following information should be recorded in the noise

measurement form.

1. Description of source(s) and surroundings

The report should include the following:
• description of the sound source(s);
• location of source(s);
• description and sketch of physical environment, including
walls, ceilings, or room contents (if appropriate). If
outdoors, trees, structures, reflecting objects,
topographical features, and any other relevant features;
• photographs if appropriate;
• air temperature and relative humidity where affected
premises are greater than 250m from source locations;
• wind speed and direction; and
• operating conditions of sound source(s).
10 Noise Measurement Manual • 3rd edition • 1 March 2000 • ISBN 0 7242 6411 6
Appendix A
Australian Standards
AS1055-1997 Acoustics — Description and measurement of
environmental noise
Part 1: General procedures
Part 2: Application to specific situations
Part 3: Acquisition of data pertinent to land use

AS1259-1990 Acoustics — Sound level meters

Part 1: Non-integrating
Part 2: Integrating-averaging

AS1633-1985 Acoustics — Glossary of terms and

related symbols

AS2659-1988 Acoustics — Guide to the use of sound

measuring equipment
Part 1: Portable sound level meters

AS/NZS 4476:1997 Acoustics — Octave-band and

fractional-octave-band-filters

Noise Measurement Manual • 3rd edition • 1 March 2000 • ISBN 0 7242 6411 6 11
Appendix B
Noise measurement form

1 Noise source

Company name:

Address:

Contact name: Position:

Telephone: Fax:

2 Location plan
Include measurement locations and numbers, north point, names of roads, streets etc. and estimated/measured
distances to closest residence/s

12 Noise Measurement Manual • 3rd edition • 1 March 2000 • ISBN 0 7242 6411 6
 o
3 Atmospheric conditions Air temperature C

Wind speed km/h Relative humidity %

Wind direction Barometric pressure hPa

4 Noise measuring equipment Type 1 Type 2

Manufacturer Model Serial number

Sound level meter

Calibrator

Frequency filter set

Level recorder

Tape recorder

5 Noise characteristics

Steady state, continuous a Intermittent c

Steady state, cyclic b Continuously fluctuating d

Noise source number and characteristics

S1 S2 S3 S4 S5 S6 S7 S8 S9 S10

Tonal adjustment [dB(A)]

Impulsive adjustment [dB(A)]

Description of noise sources

S1 S6

S2 S7

S3 S8

S4 S9

S5 S10

Noise Measurement Manual • 3rd edition • 1 March 2000 • ISBN 0 7242 6411 6 13
14
6 Noise levels Include background and all source noise levels

Meter settings: Response: Fast Slow Impulse Peak Dynamic range: dB

Weighing: A C Linear Microphone elevation m

Date: Time Measurement Noise levels dB(A) Average Comments

location number dB(A)
Source number

Calibration Adjustment =

Background

Calibration Adjustment =

Noise Measurement Manual • 3rd edition • 1 March 2000 • ISBN 0 7242 6411 6
 7 Calculations (eg distance attenuation, simultaneous operation of noise sources)

8 Noise at receiver Residential Commercial

Receiver number

R1 R2 R3 R4 R5

LAeq,T

LA10,T

LA90,T

LAmax,adj,T

9 Operation

Days of operation of noise source:

Hours of operation of noise source:

10 Degree of interference
Describe the interference that the noise would have on the conduct of activities ordinarily carried on at the
receiver’s premises.

11 Lawful uses
What are the lawful uses (zonings) permitted for premises in the vicinity of the premises being assessed?

12 Topography
Describe the topography of the area between the premises being assessed and the receiver.

Noise Measurement Manual • 3rd edition • 1 March 2000 • ISBN 0 7242 6411 6 15
 13 Complaints Number of complaints received.

Comments:

14 Other noises
Describe all the other noises ordinarily present in the vicinity of the premises being assessed.

15 Dates of occupancy
Was the noise source premises in existence before the receivers’ premises? Yes No
If yes, what have the receivers done to reduce the impact of the noise?

16 Impact
Discuss the impact of existing/proposed premises, requirements for noise control and, if required,
reduction necessary.

17 Measurement conducted by:

Name: Position:

Signed: Date:

16 Noise Measurement Manual • 3rd edition • 1 March 2000 • ISBN 0 7242 6411 6