Acoustics -- Noise from shooting ranges

This document specifies methods for recording the time history of the sound pressure produced either by shooting with calibres of less than 20Â mm, or by detonation of explosive charges of less than 50Â g TNT equivalent, within the shooting range at locations of interest, regarding the exposure to sound of the shooter, or any other person within the shooting range. The time history of the sound pressure can be the basis for further analyses of this type of sound at the locations of interest.

Acoustique -- Bruit des stands de tir

General Information

Status
Published
Publication Date
30-Jun-2021
Current Stage
5060 - Close of voting Proof returned by Secretariat
Start Date
02-Jun-2021
Completion Date
01-Jun-2021
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INTERNATIONAL ISO
STANDARD 17201-6
First edition
2021-07
Acoustics — Noise from shooting
ranges —
Part 6:
Sound pressure measurements
close to the source for determining
exposure to sound
Acoustique — Bruit des stands de tir —
Partie 6: Mesurages de la pression sonore près de la source pour
déterminer l’exposition au son
Reference number
ISO 17201-6:2021(E)
ISO 2021
---------------------- Page: 1 ----------------------
ISO 17201-6:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 17201-6:2021(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Measurement system requirements ................................................................................................................................................ 2

4.1 General ........................................................................................................................................................................................................... 2

4.2 Ranges of sound pressure levels .............................................................................................................................................. 2

4.3 Overall system description ........................................................................................................................................................... 2

4.4 Microphone and preamplifier requirements ................................................................................................................ 3

4.5 Microphone fixture .............................................................................................................................................................................. 3

4.6 Cable length ............................................................................................................................................................................................... 3

4.7 Wind screens ............................................................................................................................................................................................ 4

4.8 Data acquisition system .................................................................................................................................................................. 4

4.9 Data storage ............................................................................................................................................................................................... 4

4.10 Frequency-weighting ......................................................................................................................................................................... 4

4.11 Field calibration ..................................................................................................................................................................................... 4

5 Measurement setup ........................................................................................................................................................................................... 5

5.1 General considerations .................................................................................................................................................................... 5

5.2 Measurement location ...................................................................................................................................................................... 5

5.3 Special case: Weapons fixture .................................................................................................................................................... 5

5.4 Persons in the shooting range ................................................................................................................................................... 5

5.5 Simultaneous multi-location measurements ................................................................................................................ 6

5.6 Exception: Absence of persons influencing the exposure to sound .......................................................... 6

5.7 Microphone orientation .................................................................................................................................................................. 6

5.8 Weather and ambient conditions ............................................................................................................................................ 6

6 Documentation ....................................................................................................................................................................................................... 6

6.1 General ........................................................................................................................................................................................................... 6

6.2 Shooting range ........................................................................................................................................................................................ 6

6.3 Absorbing and reflecting elements........................................................................................................................................ 6

6.4 Sound source documentation .................................................................................................................................................... 6

6.5 Location of the primary source of the sound ................................................................................................................ 6

6.6 Shooter ........................................................................................................................................................................................................... 7

6.7 Measurement location ...................................................................................................................................................................... 7

6.8 Weather and ambient conditions ............................................................................................................................................ 7

7 Data evaluation and uncertainties ..................................................................................................................................................... 7

7.1 General ........................................................................................................................................................................................................... 7

7.2 Evaluating discrete time data ..................................................................................................................................................... 7

7.3 Frequency-weighting ......................................................................................................................................................................... 7

7.4 Measurement uncertainties ......................................................................................................................................................... 8

Annex A (informative) Slew rate limitations for impulse sound measurements ...................................................9

Annex B (informative) Calculations with discrete-time data ...................................................................................................13

Annex C (informative) Calculating C-weighted time series using a digital filter .................................................15

Bibliography .............................................................................................................................................................................................................................21

© ISO 2021 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 17201-6:2021(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/ patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/

iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 43, Acoustics, Subcommittee SC 1, Noise.

A list of all parts in the ISO 17201 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 17201-6:2021(E)
Introduction

ISO 17201-1 to ISO 17201-5 (see Clause 2 and References [2] to [5]) relate to the determination or

prediction of environmentally relevant sound immission at receiving locations outside shooting ranges.

There are countries, where the need exists also for knowledge about exposure to sound within a

shooting range at short distances from the sound source, for instance for prediction, evaluation,

assessment, control or comparison purposes.

Various methods and metrics are in use for the determination of exposure to impulsive sounds, and

these can be derived from the measurement and analysis of the time history of sound pressure at the

locations of interest.

Close to the muzzle blast or blast of an explosion, the measurement of sound pressure has particular

features to be considered. This document can be applied to both indoor and outdoor shooting ranges

that can contain different elements or usage situations. The method is applicable for locations where

persons may be present at the shooting range, including the shooter and other persons (such as an

instructor, supervisor, bystander or observer). The locations of interest include the position of the

shooter (and posture and orientation) and the position of other persons within the shooting range.

This document defines how the time history of the sound pressure at locations of interest within a

shooting range, regarding the exposure to impulsive sound of a person, can be reliably obtained.

© ISO 2021 – All rights reserved v
---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 17201-6:2021(E)
Acoustics — Noise from shooting ranges —
Part 6:
Sound pressure measurements close to the source for
determining exposure to sound
1 Scope

This document specifies methods for recording the time history of the sound pressure produced either

by shooting with calibres of less than 20 mm, or by detonation of explosive charges of less than 50 g

TNT equivalent, within the shooting range at locations of interest, regarding the exposure to sound of

the shooter, or any other person within the shooting range. The time history of the sound pressure can

be the basis for further analyses of this type of sound at the locations of interest.

2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 17201-1:2018, Acoustics — Noise from shooting ranges — Part 1: Determination of muzzle blast by

measurement
ISO 80000-8, Quantities and units — Part 8: Acoustics
IEC 60942, Electroacoustics — Sound calibrators

IEC 61094-4, Measurement microphones — Part 4: Specifications for working standard microphones

IEC 61094-6:2004, Measurement microphones — Part 6: Electrostatic actuators for determination of

frequency response
IEC 61672-1:2013, Electroacoustics — Sound level meters — Part 1: Specifications
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 80000-8 and the following

apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .or
3.1
discrete-time sound pressure signal series
sound pressure history with values given for discrete times

Note 1 to entry: In general, this time-series is the result of sampling the recorded sound pressure time-history.

Note 2 to entry: In all applications in this document, equal time spacing is assumed.

© ISO 2021 – All rights reserved 1
---------------------- Page: 6 ----------------------
ISO 17201-6:2021(E)
3.2
sampling
reduction of a continuous-time signal series to a discrete-time signal series
3.3
sample
value at a point in time within a discrete-time signal series

Note 1 to entry: Samples can be in various number formats, typically integer or real.

Note 2 to entry: Scaling and offset information is needed if samples are not stored as sound pressure values.

3.4
sampling interval
time between two adjacent values in a discrete-time signal series
Note 1 to entry: The sampling interval T is expressed in seconds.
3.5
sampling rate
number of samples (3.3) per second
Note 1 to entry: The sampling rate f is expressed in hertz.
Note 2 to entry: f = .
4 Measurement system requirements
4.1 General

This clause specifies instrumentation for measuring impulsive sounds from the sources specified in

the scope. The purpose is to enable the reliable and accurate measurement of sound pressure histories

which can be used as input to various methods for describing impulsive sound characteristics such as

[1]

sound exposure level, peak sound pressure level, A-duration, etc. as for example defined in ISO 10843 .

As this clause specifies the frequency range and other system requirements, data obtained within the

given specifications can be compared to other measurement results obtained using this method.

4.2 Ranges of sound pressure levels

The peak sound pressure level depends, among other things, on the source energy of the blast and

the distance to it. At close distances to the source, the peak sound pressure can be above 1 kPa,

corresponding to a level above 154 dB. The other parts of ISO 17201 series can only be used for sound

pressure levels below 154 dB, since these parts are concerned with sound propagation. This document

is focused on the measurement of the time history of the sound pressure; therefore no limit on the peak

sound pressure level is set.
4.3 Overall system description

The measurement system shall consist of at least a microphone with a preamplifier and a digital data

acquisition system capable of storing digital signals for later retrieval and processing.

The measurement system including the digital data acquisition system shall meet the requirements for

the limits on frequency response for Class 1 according to IEC 61672-1:2013, 5.5 using Z-weighting.

NOTE For the calculation of quantities specified in IEC 61672-1, also see Annex B.

2 © ISO 2021 – All rights reserved
---------------------- Page: 7 ----------------------
ISO 17201-6:2021(E)
4.4 Microphone and preamplifier requirements

The measurements shall be performed with a pressure type microphone meeting the requirements for

a WS3-P or WS2-P microphone as defined in IEC 61094-4. The use of a WS3-P microphone is preferred,

since the influence of the angle of incidence within the frequency range of interest is smaller compared

to a WS2-P microphone.

NOTE 1 A microphone of type WS3-P is often named ¼ inch working standard pressure microphone and

WS2-P a ½ inch working standard pressure microphone.

The microphone shall be connected to a cylindrical preamplifier with a diameter not larger than that

of the microphone. The microphone and preamplifier combination shall have the capability to measure

peak sound pressure levels in the appropriate range, with
LL≤−5dB (1)
pp,,maxOL
where
L is the peak sound pressure level to be measured, expressed in decibels;
p,max

L is the maximum peak sound pressure level at which the microphone and preamplifier com-

p,OL
bination is not overloaded, expressed in decibels
and LL≤−60dB (2)
pp,,nf max

where L is the A-weighted noise floor of the microphone and preamplifier combination, expressed

p,nf
in decibels.

NOTE 2 The A-weighted noise floor is used because this value is typically specified in microphone and

preamplifier data sheets.

A microphone and preamplifier combination capable of measuring peak sound pressure levels of at

least 165 dB is recommended.

The dynamic range of the microphone and preamplifier combination shall be at least 100 dB. The

dynamic range is the range from the highest peak sound pressure level capacity of the microphone to

the A-weighted noise floor level of the microphone and preamplifier combination.

The frequency response of the microphone and preamplifier shall be calibrated with an electrostatic

actuator according to IEC 61094-6 in the frequency range from 250 Hz to 20 kHz. This calibration

shall be performed less than 365 days before the measurements. This is defined in IEC 61094-4:2004,

Figure 2 and Table 2.

NOTE 3 The calibration according to IEC 61094-6 is usually performed by the microphone manufacturer or a

calibration laboratory.
4.5 Microphone fixture

A fixture with small influences on the measured sound field shall be used for the preamplifier and

microphone to reduce influences of the fixture on the measured sound field.
4.6 Cable length

The microphone and preamplifier shall be capable of handling the occurring signal rise times. The

signal rise time handling capacity is often determined by the preamplifier and the capacity of the cable

between the preamplifier and data acquisition system. If the cable length is increased, the cable capacity

increases and the signal rise time handling capacity of the system decreases. It is therefore important

to ensure that the signal rise time handling capacity is determined for the actual cable length used in

© ISO 2021 – All rights reserved 3
---------------------- Page: 8 ----------------------
ISO 17201-6:2021(E)

the setup. For more information about slew rate limitations and signal rise time handling capacity, see

Annex A.

NOTE In many microphone and preamplifier combinations, the limiting factor for the high peak sound

pressure handling capacity is the preamplifier, rather than the microphone.
4.7 Wind screens

It is recommended to perform measurements without a windscreen, because windscreens will change

the high frequency content of the signal and may affect the measured peak values.

However, even moderate wind speeds may cause significant wind induced noise signals from the

microphone and it is therefore recommended to check the residual noise during the measurements. If

the difference between the peak C-weighted sound pressure level during the 3 s before the impulsive

sound event and the measured C-weighted peak sound pressure value during the impulsive sound event

is less than 60 dB, the use of a windscreen is recommended. For series of measurements of impulsive

sound events with less than 3 s in between, the level of the residual background noise only needs to be

measured once.
4.8 Data acquisition system

The data acquisition system shall have a sample rate of at least 96 000 samples per second and shall be

able to store at least 10 s of continuous data. The resolution of the data acquisition system shall be at

least 20 bit.

The data acquisition system shall be equipped with an anti-aliasing filter attenuating all signal

components above the Nyquist-frequency f /2 .
For frequencies from f /2 and higher, the attenuation shall be at least 10 dB.

The attenuation of the anti-aliasing filter shall be verified either by measurement or by using the

technical specifications provided by the manufacturer.
4.9 Data storage

The recorded discrete-time sound pressure signal series shall be stored in a digital file format,

uncompressed or with lossless compression. It can be stored directly as a discrete-time sound

pressure signal series, or as a sampled data time-series. In the latter case, calibration factor and offset

information shall be provided additionally. In both cases, timing information shall be provided to link

each sample or data point to time.
If sampled data time-series are stored, the WAV-Format may be used, for example.

Timing information shall be provided either by giving the time for each data point or by giving the

sampling rate and the time of the first sample.
4.10 Frequency-weighting
All data shall be recorded and stored with Z-weighting given in IEC 61672-1.
4.11 Field calibration

The field calibration of the system shall include the response of the microphone, preamplifier, all cables

and the data acquisition system. The calibration shall be performed at either 250 Hz or 1 kHz, at a

minimum sound pressure level of 114 dB, using a sound calibrator Class 1 as defined in IEC 60942. The

calibration shall be performed before the measurements and again after the measurements, not earlier

than two hours before the measurements and not later than two hours after the measurements.

4 © ISO 2021 – All rights reserved
---------------------- Page: 9 ----------------------
ISO 17201-6:2021(E)

The calibration before the measurement may include an adjustment of sensitivity parameters. The

calibration after the measurement is a verification of calibration conformance.

The calibration, including differences between first and second calibration, shall be documented, and

this documentation shall be included with the measurement documentation.
5 Measurement setup
5.1 General considerations

The measured time history of the sound pressure from a specific weapon or explosive charge is

influenced by the acoustical environment within the specific shooting range. Any reflections and

scattering from the ground, walls or other obstacles as well as effects due to the presence of persons

are included in the measurement. For a specific weapon the result may also depend on the directivity of

the sound radiation from the weapon and the location and posture of the shooter.

The sound pressure at the ears of a person at a location of interest can be very different for the left and

right ear, and is influenced by specific details such as different head shapes and the exact orientation of

the head. Measurement setups that take all these influences into account typically provide results for

very individual events.

To enable generic and reproducible measurement results, the measurements are therefore carried out

without the presence of the person at the location at which the exposure to sound is to be determined,

and the microphone is placed where the centre of the head of that person would be.

5.2 Measurement location
To determine the exposure to sound at a location of interest
— within a specific shooting range,
— for a specific body posture, and
— for a specific source (firearm or explosive charge),

measurements are performed with a person at that location being absent, and the microphone placed

where the centre of the head would be.
5.3 Special case: Weapons fixture

To determine the exposure to sound at the location of a shooter discharging a firearm, the shooter

is absent, and the weapon is placed in a fixture and operated remotely. Only in this special case the

measurement of shooting sound shall be performed in the absence of the shooter. The microphone is

placed in the position where the centre of the head of the shooter would be.

The weapons fixture shall be constructed in such a way that the sound reflected by the fixture does not

contribute significantly to the recorded discrete-time sound pressure signal series.

5.4 Persons in the shooting range

The presence of persons in the shooting range can influence the exposure to sound at the location of

interest. As an example, if the location of interest is behind the shooter, the head and body of the shooter

is expected to significantly influence the exposure to sound at that location. Another example would be

a person between the blast source and the location of interest.

If the presence of persons in the shooting range is deemed to influence the exposure to sound at the

location of interest, the measurements shall be performed with these persons present. Therefore, if

measurements are performed in regard to a firearm, the shooter is always present if the location of

interest is not the location of the shooter itself.
© ISO 2021 – All rights reserved 5
---------------------- Page: 10 ----------------------
ISO 17201-6:2021(E)
5.5 Simultaneous multi-location measurements

Simultaneous measurements are allowed if, for the locations of interest, the presence of a person (other

than the shooter) is not deemed to influence the exposure to sound at these measurement locations. This

means that if the location of a shooter as well as the location of bystanders is of interest, two separate

measurement series should be performed, one without the shooter for this location and a second with

the shooter present but without persons present at the other locations of interest.

5.6 Exception: Absence of persons influencing the exposure to sound

Single and multi-location measurements in the absence of a person or persons which might, when

present, influence the exposure to sound at the measurement locations are allowed, but require a clear

and prominent statement in the documentation.
5.7 Microphone orientation
The microphone shall be mounted vertically, with the diaphragm facing upwards.
NOTE In terms of IEC 61672-1, the reference direction is vertical.
5.8 Weather and ambient conditions

There are no restrictions for weather and ambient conditions. It is recommended to make measurements

not likely to be affected by precipitation and or high wind conditions.
6 Documentation
6.1 General

A general description of the measurement system and the layout shall be given together with a brief

explanation of the purpose of the measurement.
6.2 Shooting range

A schematic diagram of the shooting range shall be given. The diagram shall include indications that

show the firing position of the weapon or explosive charge and positions of all persons for which

the exposure of sound is to be determined as well all other persons relevant to the measured sound

pressure.
6.3 Absorbing and reflecting elements
For elements such as the grou
...

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 17201-6
ISO/TC 43/SC 1
Acoustics — Noise from shooting
Secretariat: DIN
ranges —
Voting begins on:
2021-04-06
Part 6:
Voting terminates on:
Sound pressure measurements
2021-06-01
close to the source for determining
exposure to sound
Acoustique — Bruit des stands de tir —
Partie 6: Mesurages de la pression sonore près de la source pour
déterminer l’exposition au son
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/FDIS 17201-6:2021(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN-
DARDS TO WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS. ISO 2021
---------------------- Page: 1 ----------------------
ISO/FDIS 17201-6:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/FDIS 17201-6:2021(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Measurement system requirements ................................................................................................................................................ 2

4.1 General ........................................................................................................................................................................................................... 2

4.2 Ranges of sound pressure levels .............................................................................................................................................. 2

4.3 Overall system description ........................................................................................................................................................... 2

4.4 Microphone and preamplifier requirements ................................................................................................................ 3

4.5 Microphone fixture .............................................................................................................................................................................. 3

4.6 Cable length ............................................................................................................................................................................................... 3

4.7 Wind screens ............................................................................................................................................................................................ 4

4.8 Data acquisition system .................................................................................................................................................................. 4

4.9 Data storage ............................................................................................................................................................................................... 4

4.10 Frequency-weighting ......................................................................................................................................................................... 4

4.11 Field calibration ..................................................................................................................................................................................... 4

5 Measurement setup ........................................................................................................................................................................................... 5

5.1 General considerations .................................................................................................................................................................... 5

5.2 Measurement location ...................................................................................................................................................................... 5

5.3 Special case: Weapons fixture .................................................................................................................................................... 5

5.4 Persons in the shooting range ................................................................................................................................................... 5

5.5 Simultaneous multi-location measurements ................................................................................................................ 6

5.6 Exception: Absence of persons influencing the exposure to sound .......................................................... 6

5.7 Microphone orientation .................................................................................................................................................................. 6

5.8 Weather and ambient conditions ............................................................................................................................................ 6

6 Documentation ....................................................................................................................................................................................................... 6

6.1 General ........................................................................................................................................................................................................... 6

6.2 Shooting range ........................................................................................................................................................................................ 6

6.3 Absorbing and reflecting elements........................................................................................................................................ 6

6.4 Sound source documentation .................................................................................................................................................... 6

6.5 Location of the primary source of the sound ................................................................................................................ 6

6.6 Shooter ........................................................................................................................................................................................................... 7

6.7 Measurement location ...................................................................................................................................................................... 7

6.8 Weather and ambient conditions ............................................................................................................................................ 7

7 Data evaluation and uncertainties ..................................................................................................................................................... 7

7.1 General ........................................................................................................................................................................................................... 7

7.2 Evaluating discrete time data ..................................................................................................................................................... 7

7.3 Frequency-weighting ......................................................................................................................................................................... 7

7.4 Measurement uncertainties ......................................................................................................................................................... 8

Annex A (informative) Slew rate limitations for impulse sound measurements ...................................................9

Annex B (informative) Calculations with discrete-time data ...................................................................................................13

Annex C (informative) Calculating C-weighted time series using a digital filter .................................................15

Bibliography ...................................................................................................................................................................................................................... 21

© ISO 2021 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO/FDIS 17201-6:2021(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/ patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/

iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 43, Acoustics, Subcommittee SC 1, Noise.

A list of all parts in the ISO 17201 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/FDIS 17201-6:2021(E)
Introduction

ISO 17201-1 to ISO 17201-5 (see Clause 2 and References [2] to [5]) relate to the determination or

prediction of environmentally relevant sound immission at receiving locations outside shooting ranges.

There are countries, where the need exists also for knowledge about exposure to sound within a

shooting range at short distances from the sound source, for instance for prediction, evaluation,

assessment, control or comparison purposes.

Various methods and metrics are in use for the determination of exposure to impulsive sounds, and

these can be derived from the measurement and analysis of the time history of sound pressure at the

locations of interest.

Close to the muzzle blast or blast of an explosion, the measurement of sound pressure has particular

features to be considered. This document can be applied to both indoor and outdoor shooting ranges

that can contain different elements or usage situations. The method is applicable for locations where

persons may be present at the shooting range, including the shooter and other persons (such as an

instructor, supervisor, bystander or observer). The locations of interest include the position of the

shooter (and posture and orientation) and the position of other persons within the shooting range.

This document defines how the time history of the sound pressure at locations of interest within a

shooting range, regarding the exposure to impulsive sound of a person, can be reliably obtained.

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FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 17201-6:2021(E)
Acoustics — Noise from shooting ranges —
Part 6:
Sound pressure measurements close to the source for
determining exposure to sound
1 Scope

This document specifies methods for recording the time history of the sound pressure produced either

by shooting with calibres of less than 20 mm, or by detonation of explosive charges of less than 50 g

TNT equivalent, within the shooting range at locations of interest, regarding the exposure to sound of

the shooter, or any other person within the shooting range. The time history of the sound pressure can

be the basis for further analyses of this type of sound at the locations of interest.

2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 17201-1:2018, Acoustics — Noise from shooting ranges — Part 1: Determination of muzzle blast by

measurement
ISO 80000-8, Quantities and units — Part 8: Acoustics
IEC 60942, Electroacoustics — Sound calibrators

IEC 61094-4, Measurement microphones — Part 4: Specifications for working standard microphones

IEC 61094-6:2004, Measurement microphones — Part 6: Electrostatic actuators for determination of

frequency response
IEC 61672-1:2013, Electroacoustics — Sound level meters — Part 1: Specifications
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 80000-8 and the following apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .or
3.1
discrete-time sound pressure signal series
sound pressure history with values given for discrete times

Note 1 to entry: In general, this time-series is the result of sampling the recorded sound pressure time-history.

Note 2 to entry: In all applications in this document, equal time spacing is assumed.

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ISO/FDIS 17201-6:2021(E)
3.2
sampling
reduction of a continuous-time signal series to a discrete-time signal series
3.3
sample
value at a point in time within a discrete-time signal series

Note 1 to entry: Samples can be in various number formats, typically integer or real.

Note 2 to entry: Scaling and offset information is needed if samples are not stored as sound pressure values.

3.4
sampling interval
time between two adjacent values in a discrete-time signal series
Note 1 to entry: The sampling interval T is expressed in seconds.
3.5
sampling rate
number of samples (3.3) per second
Note 1 to entry: The sampling rate f is expressed in hertz.
Note 2 to entry: f = .
4 Measurement system requirements
4.1 General

This clause specifies instrumentation for measuring impulsive sounds from the sources specified in

the scope. The purpose is to enable the reliable and accurate measurement of sound pressure histories

which can be used as input to various methods for describing impulsive sound characteristics such as

[1]

sound exposure level, peak sound pressure level, A-duration, etc. as for example defined in ISO 10843 .

As this clause specifies the frequency range and other system requirements, data obtained within the

given specifications can be compared to other measurement results obtained using this method.

4.2 Ranges of sound pressure levels

The peak sound pressure level depends, among other things, on the source energy of the blast and

the distance to it. At close distances to the source, the peak sound pressure can be above 1 kPa,

corresponding to a level above 154 dB. The other parts of ISO 17201 series can only be used for sound

pressure levels below 154 dB, since these parts are concerned with sound propagation. This document

is focused on the measurement of the time history of the sound pressure; therefore no limit on the peak

sound pressure level is set.
4.3 Overall system description

The measurements system shall consist of at least a microphone with a preamplifier and a digital data

acquisition system capable of storing digital signals for later retrieval and processing.

The measurement system including the digital data acquisition system shall meet the requirements for

the limits on frequency response for Class 1 according to IEC 61672-1:2013, 5.5 using Z-weighting.

NOTE For the calculation of quantities specified in IEC 61672-1, also see Annex B.

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ISO/FDIS 17201-6:2021(E)
4.4 Microphone and preamplifier requirements

The measurements shall be performed with a pressure type microphone meeting the requirements for

a WS3-P or WS2-P microphone as defined in IEC 61094-4. The use of a WS3-P microphone is preferred,

since the influence of the angle of incidence within the frequency range of interest is smaller compared

to a WS2-P microphone.

NOTE 1 A microphone of type WS3-P is often named ¼ inch working standard pressure microphone and

WS2-P a ½ inch working standard pressure microphone.

The microphone shall be connected to a cylindrical preamplifier with a diameter not larger than that

of the microphone. The microphone and preamplifier combination shall have the capability to measure

peak sound pressure levels in the appropriate range, with
LL≤−5dB (1)
pp,,maxOL
where
L is the peak sound pressure level to be measured, expressed in decibels;
p,max

L is the maximum peak sound pressure level at which the microphone and preamplifier com-

p,OL
bination is not overloaded, expressed in decibels.
LL≤−60dB (2)
pp,,nf max

where L is the A-weighted noise floor of the microphone and preamplifier combination, expressed

p,nf
in decibels.

NOTE 2 The A-weighted noise floor is used because this value is typically specified in microphone and

preamplifier data sheets.

A microphone and preamplifier combination capable of measuring peak sound pressure levels of at

least 165 dB is recommended.

The dynamic range of the microphone and preamplifier combination shall be at least 100 dB. The

dynamic range is the range from the highest peak sound pressure level capacity of the microphone to

the A-weighted noise floor level of the microphone and preamplifier combination.

The frequency response of the microphone and preamplifier shall be calibrated with an electrostatic

actuator according to IEC 61094-6 in the frequency range from 250 Hz to 20 kHz. This calibration

shall be performed less than 365 days before the measurements. This is defined in IEC 61094-4:2004,

Figure 2 and Table 2.

NOTE 3 The calibration according to IEC 61094-6 is usually performed by the microphone manufacturer or a

calibration laboratory.
4.5 Microphone fixture

A fixture with small influences on the measured sound field shall be used for the preamplifier and

microphone to reduce influences of the fixture on the measured sound field.
4.6 Cable length

The microphone and preamplifier shall be capable of handling the occurring signal rise times. The

signal rise time handling capacity is often determined by the preamplifier and the capacity of the cable

between the preamplifier and data acquisition system. If the cable length is increased, the cable capacity

increases and the signal rise time handling capacity of the system decreases. It is therefore important

to ensure that the signal rise time handling capacity is determined for the actual cable length used in

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ISO/FDIS 17201-6:2021(E)

the setup. For more information about slew rate limitations and signal rise time handling capacity, see

Annex A.

NOTE In many microphone and preamplifier combinations, the limiting factor for the high peak sound

pressure handling capacity is the preamplifier, rather than the microphone.
4.7 Wind screens

It is recommended to perform measurements without a windscreen, because windscreens will change

the high frequency content of the signal and may affect the measured peak values.

However, even moderate wind speeds may cause significant wind induced noise signals from the

microphone and it is therefore recommended to check the residual noise during the measurements. If

the difference between the peak C-weighted sound pressure level during the 3 s before the impulsive

sound event and the measured C-weighted peak sound pressure value during the impulsive sound event

is less than 60 dB, the use of a windscreen is recommended. For series of measurements of impulsive

sound events with less than 3 s in between, the level of the residual background noise only needs to be

measured once.
4.8 Data acquisition system

The data acquisition system shall have a sample rate of at least 96 000 samples per second and shall be

able to store at least 10 s of continuous data. The resolution of the data acquisition system shall be at

least 20 bit.

The data acquisition system shall be equipped with an anti-aliasing filter attenuating all signal

components above the Nyquist-frequency f /2 .
For frequencies from f /2 and higher, the attenuation shall be at least 10 dB.

The attenuation of the anti-aliasing filter shall be verified either by measurement or by using the

technical specifications provided by the manufacturer.
4.9 Data storage

The recorded discrete-time sound pressure signal series shall be stored in a digital file format,

uncompressed or with lossless compression. It can be stored directly as a discrete-time sound

pressure signal series, or as a sampled data time-series. In the latter case, calibration factor and offset

information shall be provided additionally. In both cases, timing information shall be provided to link

each sample or data point to time.
If sampled data time-series are stored, the WAV-Format may be used, for example.

Timing information shall be provided either by giving the time for each data point or by giving the

sampling rate and the time of the first sample.
4.10 Frequency-weighting
All data shall be recorded and stored with Z-weighting given in IEC 61672-1.
4.11 Field calibration

The field calibration of the system shall include the response of the microphone, preamplifier, all cables

and the data acquisition system. The calibration shall be performed at either 250 Hz or 1 kHz, at a

minimum sound pressure level of 114 dB, using a sound calibrator Class 1 as defined in IEC 60942. The

calibration shall be performed before the measurements and again after the measurements, not earlier

than two hours before the measurements and not later than two hours after the measurements.

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ISO/FDIS 17201-6:2021(E)

The calibration before the measurement may include an adjustment of sensitivity parameters. The

calibration after the measurement is a verification of calibration conformance.

The calibration, including differences between first and second calibration, shall be documented, and

this documentation shall be included with the measurement documentation.
5 Measurement setup
5.1 General considerations

The measured time history of the sound pressure from a specific weapon or explosive charge is

influenced by the acoustical environment within the specific shooting range. Any reflections and

scattering from the ground, walls or other obstacles as well as effects due to the presence of persons

are included in the measurement. For a specific weapon the result may also depend on the directivity of

the sound radiation from the weapon and the location and posture of the shooter.

The sound pressure at the ears of a person at a location of interest can be very different for the left and

right ear, and is influenced by specific details such as different head shapes and the exact orientation of

the head. Measurement setups that take all these influences into account typically provide results for

very individual events.

To enable generic and reproducible measurement results, the measurements are therefore carried out

without the presence of the person at the location at which the exposure to sound is to be determined,

and the microphone is placed where the centre of the head of that person would be.

5.2 Measurement location
To determine the exposure to sound at a location of interest
— within a specific shooting range,
— for a specific body posture, and
— for a specific source (firearm or explosive charge),

measurements are performed with a person at that location being absent, and the microphone placed

where the centre of the head would be.
5.3 Special case: Weapons fixture

To determine the exposure to sound at the location of a shooter discharging a firearm, the shooter

is absent, and the weapon is placed in a fixture and operated remotely. Only in this special case the

measurement of shooting sound shall be performed in the absence of the shooter. The microphone is

placed in the position where the centre of the head of the shooter would be.

The weapons fixture shall be constructed in such a way that the sound reflected by the fixture does not

contribute significantly to the recorded discrete-time sound pressure signal series.

5.4 Persons in the shooting range

The presence of persons in the shooting range can influence the exposure to sound at the location of

interest. As an example, if the location of interest is behind the shooter, the head and body of the shooter

is expected to significantly influence the exposure to sound at that location. Another example would be

a person between the blast source and the location of interest.

If the presence of persons in the shooting range is deemed to influence the exposure to sound at the

location of interest, the measurements shall be performed with these persons present. Therefore, if

measurements are performed in regard to a firearm, the shooter is always present if the location of

interest is not the location of the shooter itself.
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ISO/FDIS 17201-6:2021(E)
5.5 Simultaneous multi-location measurements

Simultaneous measurements are allowed if, for the locations of interest, the presence of a person (other

than the shooter) is not deemed to influence the exposure to sound at these measurement locations. This

means that if the location of a shooter as well as the location of bystanders is of interest, two separate

measurement series should be performed, one without the shooter for this location and a second with

the shooter present but without persons present at the other locations of interest.

5.6 Exception: Absence of persons influencing the exposure to sound

Single and multi-location measurements in the absence of a person or persons which might, when

present, influence the exposure to sound at the measurement locations are allowed, but require a clear

and prominent statement in the documentation.
5.7 Microphone orientation
The microphone shall be mounted vertically, with the diaphragm facing upwards.
NOTE In terms of IEC 61672-1, the reference direction is vertical.
5.8 Weather and ambient conditions

There are no restrictions for weather and ambient conditions. It is recommended to make measurements

not lik
...

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