Acoustics - Audiometric test methods - Part 2: Sound field audiometry with pure-tone and narrow-band test signals (ISO 8253-2:2009)

ISO 8253-2:2009 specifies relevant test signal characteristics, requirements for free, diffuse, and quasi‑free sound fields, and procedures for sound field audiometry using pure tones, frequency-modulated tones or other narrow-band test signals presented by means of one or more loudspeakers. The primary purpose is the determination of hearing threshold levels in the frequency range 125 Hz to 8 000 Hz, but this range can be extended to 20 Hz to 16 000 Hz.
ISO 8253-2:2009 does not include specifications for the use of hand-held loudspeakers. Speech as a test signal is not covered.
The purpose of ISO 8253-2:2009 is to ensure that tests of hearing, using sound field audiometry, give as high a degree of accuracy and reproducibility as possible.
Examples of graphical representations of the results are given.

Akustik - Audiometrische Prüfverfahren - Teil 2: Schallfeld-Audiometrie mit reinen Tönen und schmalbandigen Prüfsignalen (ISO 8253-2:2009)

Dieser Teil von ISO 8253 legt wesentliche Eigenschaften des Prüfsignals, Anforderungen an das freie, dif-fuse, und quasi-freie Schallfeld und Verfahren der Schallfeld-Audiometrie mit reinen Tönen, frequenzmodu-lierten Tönen oder anderen schmalbandigen Prüfsignalen fest, die über einen oder mehrere Lautsprecher dargeboten werden. Der hauptsächliche Verwendungszweck ist die Bestimmung von Hörschwellenpegeln im Frequenzbereich von 125 Hz bis 8 000 Hz. Dieser Bereich kann aber auf 20 Hz bis 16 000 Hz erweitert wer-den.
Dieser Teil von ISO 8253 enthält keine Festlegungen zur Verwendung von handgehaltenen Lautsprechern. Sprache als Prüfsignal wird hier nicht behandelt.
Der Zweck dieses Teils von ISO 8253 ist es, sicherzustellen, dass Hörprüfungen mittels Schallfeld-Audio-metrie höchstmögliche Genauigkeit und Reproduzierbarkeit ergeben.
Beispiele für die grafische Darstellung der Ergebnisse und Literaturhinweise werden in Anhang A angegeben.

Acoustique - Méthodes d'essais audiométriques - Partie 2: Audiométrie en champ acoustique avec des sons purs et des bruits à bande étroite comme signaux d'essai (ISO 8253-2:2009)

L'ISO 8253-2:2009 spécifie les caractéristiques utiles des signaux d'essai, les exigences relatives aux champs acoustiques libre, diffus et quasi libre, ainsi que les modes opératoires s'appliquant à l'audiométrie en champ acoustique réalisée à l'aide de sons purs, de sons modulés en fréquence ou d'autres signaux d'essai de bande étroite émis par un ou plusieurs haut-parleurs. L'objectif principal est la détermination des niveaux liminaires d'audition dans la gamme de fréquences comprises entre 125 Hz et 8 000 Hz, celle-ci pouvant être étendue entre 20 Hz et 16 000 Hz.
L'ISO 8253-2:2009 ne comporte pas de spécifications relatives à l'utilisation de haut-parleurs portatifs. Elle ne couvre pas les essais vocaux.
L'objectif de l'ISO 8253-2:2009 est de garantir un degré de précision et de reproductibilité des essais d'audition effectués par audiométrie en champ acoustique aussi élevé que possible.
Des exemples de représentations graphiques des résultats d'essai y sont donnés.

Akustika - Avdiometrijske preskusne metode - 2. del: Avdiometrija v zvočnem polju s čistimi toni in ozkopasovnimi preskusnimi signali (ISO 8253-2:2009)

Ta del ISO 8253 določa ustrezne lastnosti preskusnega signala, zahteve za prosto, difuzno in navidezno prosto zvočno polje ter postopke za avdiometrijo zvočnega polja z uporabo čistih tonov, frekvenčno moduliranih tonov ali drugih ozkopasovnih preskusnih signalov, ki jih proizvaja eden ali več zvočnikov. Glavni namen je ugotavljanje ravni slušnega praga v frekvenčnem območju med 125 Hz in 8.000 Hz, vendar se lahko razširi na območje med 20 Hz in 16.000 Hz. Ta del ISO 8253 ne vključuje specifikacij za uporabo ročnih zvočnikov. Govor kot preskusni signal ni vključen. Namen tega dela ISO 8253 je zagotoviti, da so preskusi sluha z uporabo avdiometrije z zvočnim poljem čim bolj natančni in ponovljivi. Primeri grafičnih prikazov rezultatov so podani v Dodatku A.

General Information

Status
Published
Publication Date
14-Dec-2009
Technical Committee
Current Stage
6060 - Definitive text made available (DAV) - Publishing
Due Date
15-Dec-2009
Completion Date
15-Dec-2009

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SLOVENSKI STANDARD
SIST EN ISO 8253-2:2010
01-april-2010
1DGRPHãþD
SIST EN ISO 8253-2:1999
$NXVWLND$YGLRPHWULMVNHSUHVNXVQHPHWRGHGHO$YGLRPHWULMDY]YRþQHP
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Acoustics - Audiometric test methods - Part 2: Sound field audiometry with pure-tone and

narrow-band test signals (ISO 8253-2:2009)

Akustik - Audiometrische Prüfverfahren - Teil 2: Schallfeld-Audiometrie mit reinen Tönen

und schmalbandigen Prüfsignalen (ISO 8253-2:2009)
Acoustique - Méthodes d'essais audiométriques - Partie 2: Audiométrie en champ

acoustique avec des sons purs et des bruits à bande étroite comme signaux d'essai (ISO

8253-2:2009)
Ta slovenski standard je istoveten z: EN ISO 8253-2:2009
ICS:
13.140 Vpliv hrupa na ljudi Noise with respect to human
beings
17.140.01 $NXVWLþQDPHUMHQMDLQ Acoustic measurements and
EODåHQMHKUXSDQDVSORãQR noise abatement in general
SIST EN ISO 8253-2:2010 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 8253-2:2010
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SIST EN ISO 8253-2:2010
EUROPEAN STANDARD
EN ISO 8253-2
NORME EUROPÉENNE
EUROPÄISCHE NORM
December 2009
ICS 13.140 Supersedes EN ISO 8253-2:1998
English Version
Acoustics - Audiometric test methods - Part 2: Sound field
audiometry with pure-tone and narrow-band test signals (ISO
8253-2:2009)

Acoustique - Méthodes d'essais audiométriques - Partie 2: Akustik - Audiometrische Prüfverfahren - Teil 2: Schallfeld-

Audiométrie en champ acoustique avec des sons purs et Audiometrie mit reinen Tönen und schmalbandigen

des bruits à bande étroite comme signaux d'essai (ISO Prüfsignalen (ISO 8253-2:2009)

8253-2:2009)
This European Standard was approved by CEN on 26 October 2009.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European

Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national

standards may be obtained on application to the CEN Management Centre or to any CEN member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation

under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as the

official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,

France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,

Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: Avenue Marnix 17, B-1000 Brussels

© 2009 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 8253-2:2009: E

worldwide for CEN national Members.
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SIST EN ISO 8253-2:2010
EN ISO 8253-2:2009 (E)
Contents Page

Foreword ..............................................................................................................................................................3

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SIST EN ISO 8253-2:2010
EN ISO 8253-2:2009 (E)
Foreword

This document (EN ISO 8253-2:2009) has been prepared by Technical Committee ISO/TC 43 "Acoustics" in

collaboration with the Technical Committee CEN/TC 211 “Acoustics” the secretariat of which is held by DS.

This European Standard shall be given the status of a national standard, either by publication of an identical

text or by endorsement, at the latest by June 2010, and conflicting national standards shall be withdrawn at

the latest by June 2010.

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

rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.

This document supersedes EN ISO 8253-2:1998.

According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following

countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech

Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,

Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,

Sweden, Switzerland and the United Kingdom.
Endorsement notice

The text of ISO 8253-2:2009 has been approved by CEN as a EN ISO 8253-2:2009 without any modification.

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SIST EN ISO 8253-2:2010
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SIST EN ISO 8253-2:2010
INTERNATIONAL ISO
STANDARD 8253-2
Second edition
2009-12-15
Acoustics — Audiometric test methods —
Part 2:
Sound field audiometry with pure-tone
and narrow-band test signals
Acoustique — Méthodes d'essais audiométriques —
Partie 2: Audiométrie en champ acoustique avec des sons purs et des
bruits à bande étroite comme signaux d'essai
Reference number
ISO 8253-2:2009(E)
ISO 2009
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SIST EN ISO 8253-2:2010
ISO 8253-2:2009(E)
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All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,

electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or

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Published in Switzerland
ii © ISO 2009 – All rights reserved
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SIST EN ISO 8253-2:2010
ISO 8253-2:2009(E)
Contents Page

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

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

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

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

3 Terms and definitions ...........................................................................................................................2

4 Test signal characteristics ...................................................................................................................3

4.1 General ...................................................................................................................................................3

4.2 Pure tones ..............................................................................................................................................3

4.3 FM tones.................................................................................................................................................4

4.4 Narrow bands of noise..........................................................................................................................4

4.5 Harmonic distortion ..............................................................................................................................4

4.6 Signal gating ..........................................................................................................................................5

4.7 Signal level control................................................................................................................................5

4.8 Means and scales for calibration.........................................................................................................5

5 Sound field characteristics...................................................................................................................6

5.1 General ...................................................................................................................................................6

5.2 Free sound field.....................................................................................................................................6

5.3 Diffuse sound field ................................................................................................................................6

5.4 Quasi-free sound field...........................................................................................................................7

6 Ambient noise levels in the test room.................................................................................................7

7 Preparation and instruction of test subject........................................................................................7

8 Determination of hearing threshold level ...........................................................................................8

8.1 General ...................................................................................................................................................8

8.2 Monaural testing....................................................................................................................................8

8.3 Binaural testing .....................................................................................................................................8

9 Testing with a hearing aid ....................................................................................................................8

10 Screening audiometry...........................................................................................................................8

11 Reporting of data.................................................................................................................................10

11.1 General .................................................................................................................................................10

11.2 Equipment calibrated by hearing level..............................................................................................10

11.3 Equipment calibrated by sound pressure level ...............................................................................10

12 Maintenance and calibration of equipment ......................................................................................10

12.1 General .................................................................................................................................................10

12.2 Intervals between tests.......................................................................................................................10

12.3 Stage A: routine examination and listening tests............................................................................11

12.4 Stage B: periodic electroacoustic tests............................................................................................11

12.5 Stage C: basic calibration tests .........................................................................................................12

Annex A (informative) Graphical display of results.......................................................................................13

Annex B (informative) Correction values for 45° and 90° angles of incidence...........................................15

Bibliography......................................................................................................................................................16

© ISO 2009 – All rights reserved iii
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SIST EN ISO 8253-2:2010
ISO 8253-2:2009(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.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.

The main task of technical committees is to prepare International Standards. Draft International Standards

adopted by the technical committees are circulated to the member bodies for voting. Publication as an

International Standard requires approval by at least 75 % of the member bodies casting a vote.

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.

ISO 8253-2 was prepared by Technical Committee ISO/TC 43, Acoustics.

This second edition cancels and replaces the first edition (ISO 8253-2:1992), of which it constitutes a minor

revision.

ISO 8253 consists of the following parts, under the general title Acoustics — Audiometric test methods:

⎯ Part 1: Basic pure-tone air and bone conduction threshold audiometry
⎯ Part 2: Sound field audiometry with pure-tone and narrow-band test signals
⎯ Part 3: Speech audiometry
iv © ISO 2009 – All rights reserved
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SIST EN ISO 8253-2:2010
ISO 8253-2:2009(E)
Introduction

ISO 8253-1 covers procedures for the determination of thresholds of hearing using pure tones presented to

the subject by means of earphone or bone vibrator.

This part of ISO 8253 covers procedures for the determination of thresholds of hearing in a sound field. In

general, sound field testing implies binaural Iistening to a test signal, presented by means of one or more

loudspeakers in a test room. The test signal may be a pure tone, a frequency-modulated tone or a narrow

band of noise. The acoustical characteristics of the sound field are determined by the choice of test signal, by

the number and acoustical properties of the loudspeakers used, as well as by the acoustical characteristics of

the test room.

Sound field audiometry may be used for various purposes, e.g. the evaluation of hearing acuity in young

children and the determination of the functional gain of a hearing aid when worn by a particular listener.

© ISO 2009 – All rights reserved v
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SIST EN ISO 8253-2:2010
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SIST EN ISO 8253-2:2010
INTERNATIONAL STANDARD ISO 8253-2:2009(E)
Acoustics — Audiometric test methods —
Part 2:
Sound field audiometry with pure-tone and narrow-band test
signals
1 Scope

This part of ISO 8253 specifies relevant test signal characteristics, requirements for free, diffuse, and

quasi-free sound fields, and procedures for sound field audiometry using pure tones, frequency-modulated

tones or other narrow-band test signals presented by means of one or more loudspeakers. The primary

purpose is the determination of hearing threshold levels in the frequency range 125 Hz to 8 000 Hz, but this

range can be extended to 20 Hz to 16 000 Hz.

This part of ISO 8253 does not include specifications for the use of hand-held loudspeakers. Speech as a test

signal is not covered.

The purpose of this part of ISO 8253 is to ensure that tests of hearing, using sound field audiometry, give as

high a degree of accuracy and reproducibility as possible.
Examples of graphical representations of the results are given in Annex A.
2 Normative references

The following referenced documents are indispensable for the application 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 226, Acoustics — Normal equal-loudness-level contours
ISO 266, Acoustics — Preferred frequencies

ISO 389-7, Acoustics — Reference zero for the calibration of audiometric equipment — Part 7: Reference

threshold of hearing under free-field and diffuse-field listening conditions

ISO 8253-1:— , Acoustics — Audiometric test methods — Part 1: Basic pure-tone air and bone conduction

threshold audiometry

IEC 60581-7:1986, High fidelity audio equipment and systems — Minimum performance requirements —

Part 7: Loudspeakers

IEC 60645-1, Electroacoustics — Audiometric equipment — Part 1: Pure-tone audiometers

IEC 61672-1, Electroacoustics — Sound level meters — Part 1: Specifications
1) To be published. (Revision of ISO 8253-1:1989)
© ISO 2009 – All rights reserved 1
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SIST EN ISO 8253-2:2010
ISO 8253-2:2009(E)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
air conduction
transmission of signal through the external and middle ear to the inner ear
3.2
otologically normal person

person in a normal state of health who is free from all signs or symptoms of ear disease and from obstructing

wax in the ear canal, and who has no history of undue exposure to noise, exposure to potentially ototoxic

drugs, or of familial hearing loss
3.3
reference point

midpoint of a straight line connecting the ear canal openings of the listener when positioned in the Iistening

position in the sound field
3.4
reference axis
axis perpendicular to the radiating surface of the loudspeaker

NOTE 1 For single radiator or horn loudspeakers, the axis passes through the geometric centre of the diaphragm or

the horn.

NOTE 2 For multi-unit loudspeakers, the position of the axis is defined by the manufacturer.

3.5
threshold of hearing

level of a sound at which, under specified conditions, a person gives 50 % of correct detection responses on

repeated trials
3.6
threshold sound pressure level

for a given listener, a specified signal and a specified manner of signal presentation, sound pressure level at

the reference point (3.3) in the specific sound field, in the absence of the listener, which in the presence of

the listener in the test position would correspond to the threshold of hearing (3.5) of the listener

3.7
reference threshold sound pressure level

for a specific signal and a specified manner of signal presentation, median value of the threshold sound

pressure levels (3.6) of a sufficiently large number under test of otologically normal persons (3.2), of both

genders, aged between 18 years and 25 years inclusive, expressing the threshold of hearing (3.5) at the

reference point (3.3) in the specific sound field
3.8
hearing level

for a specified signal and a specified manner of signal presentation, sound pressure level of this signal at the

reference point (3.3) in the specific sound field minus the appropriate reference threshold sound pressure

level (3.7)
3.9
hearing threshold level

for a specified signal and a specified sound field, threshold of hearing (3.5) expressed either as hearing

level (3.8) or as sound pressure level
2 © ISO 2009 – All rights reserved
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SIST EN ISO 8253-2:2010
ISO 8253-2:2009(E)
3.10
carrier frequency of a frequency-modulated tone
average value of the periodically varying tone frequency
NOTE The carrier frequency is designated as the nominal test frequency.
3.11
frequency deviation

maximum difference between the instantaneous frequency of the frequency-modulated tone and the carrier

frequency
3.12
free sound field

sound field where the boundaries of the room exert a negligible effect on the sound waves

3.13
quasi-free sound field

sound field where the boundaries of the room exert only a moderate effect on the sound waves

NOTE The requirements for a quasi-free sound field are specified in 5.4.
3.14
diffuse sound field

sound field which in a given region has statistically uniform energy density, for which the directions of

propagation at any point are randomly distributed
3.15
white noise
noise whose power spectral density is independent of frequency
3.16
noise bandwidth
difference between the upper and lower band-edge frequencies of a noise band

NOTE At these frequencies the power spectral density of the noise is reduced to one-half of its average within the

noise band.
3.17
centre frequency of a noise band

geometric mean of the band-edge frequencies which define the noise bandwidth (3.16)

3.18
functional gain of a hearing aid

for a specified test signal, a specified type of sound field, a specified manner of signal presentation, and for a

particular listener, difference in thresholds of hearing of the listener with and without the hearing aid

4 Test signal characteristics
4.1 General

This part of ISO 8253 covers test signals that are either pure tones, frequency-modulated (FM) tones or

narrow bands of noise.
4.2 Pure tones

Pure tones shall be used only in a free sound field which is in accordance with the specifications given in 5.2.

NOTE In other types of sound field, pure tones may show large spatial variations in sound pressure level due to

standing waves.
© ISO 2009 – All rights reserved 3
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SIST EN ISO 8253-2:2010
ISO 8253-2:2009(E)

When test tones of fixed frequencies are used, they shall be chosen from the audiometric test frequencies

given in IEC 60645-1 or the frequencies given in ISO 266.

The actual frequency shall be within ± 1,5 % of the nominal frequency. This corresponds to the specification of

an audiometer complying with the requirements of IEC 60645-1, type 1 and type 2.
4.3 FM tones
FM tones are defined by the following characteristics, which shall be reported:
a) carrier frequency;
b) waveform of modulating signal;
c) repetition rate of modulating signal;
d) frequency deviation.

The carrier frequency shall be chosen from the audiometric test frequencies as specified in IEC 60645-1 or

the frequencies given in ISO 266.

The waveform of the modulating signal shall be either sinusoidal or triangular. The triangular waveform shall

have symmetrical rising and falling portions on a linear or on a logarithmic frequency scale.

The carrier frequency shall be within ± 3 % of its nominal frequency.

The repetition rate of the modulating signal shall be within the range 4 Hz to 20 Hz with a tolerance of ± 10 %

of its nominal value.

The frequency deviation shall be in the range ± 2,5 % to ± 12,5 % with a tolerance of ± 10 % of its nominal

value.

If the modulating waveform is sinusoidal, its total harmonic distortion shall not exceed 5 %. If it is triangular, its

ramps shall not deviate from a linear form by more than 5 % of its amplitude. For the triangular waveform, the

durations of the rising and falling portions shall not differ by more than 10 %.
4.4 Narrow bands of noise

The centre frequency and the bandwidth of a narrow band of noise shall comply with the specifications for

narrow-band masking noise according to IEC 60645-1. The centre frequency and the bandwidth shall be

reported.

NOTE 1 When bandwidths exceed one-third octave, reference threshold sound pressure levels may differ from those

valid for bandwidths up to one-third octave.

NOTE 2 Signal power outside the passband, which is mainly determined by the slopes and stop-band rejection

characteristics of the filter, may influence the results of sound field audiometry, in particular on hearing-impaired test

subjects.
4.5 Harmonic distortion

If pure tones are available as test signals, the linearity of the complete system shall be such that the total

harmonic distortion does not exceed 5 % at 125 Hz and 3 % at 250 Hz, 500 Hz and 1 000 Hz when measured

acoustically at the reference point in the test room. These conditions shall be met over the whole dynamic

range available.

NOTE It is usually sufficient to measure the harmonic distortion at the maximum available output sound pressure

level.
4 © ISO 2009 – All rights reserved
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SIST EN ISO 8253-2:2010
ISO 8253-2:2009(E)

The harmonic distortion of loudspeakers can only be tested in a free sound field. Where only a quasi-free or a

diffuse sound field is available, harmonic distortion may be measured electrically across the loudspeaker input

terminal. The total harmonic distortion shall be less than 1 % and the loudspeaker shall comply with the

specifications given in IEC 60581-7:1986, Clause 10.

lf pure tones are not avaiIable as test signals, the linearity of the equipment shall be tested by connecting an

external pure-tone generator to replace the original test signal source.

When FM tones are used as test signals, the r.m.s. output level of the external pure-tone generator shall be

equal to that delivered by the test signal source when in normal use.

When narrow bands of noise are used as test signals, the output of the external pure-tone generator shall be

set to a level 9 dB above the root mean square (r.m.s.) value delivered by the test signal source when in

normal use.
4.6 Signal gating

The signal shall be either presented as singular sound bursts of a duration in the range 1 s to 2 s or

repeatedly gated on and off. The requirements given in IEC 60645-1 regarding rise and fall times, on/off-times

and on/off ratio as well as under- and overshoot shall be complied with when measured electrically at the

loudspeaker terminals with pure tones as test signals.

NOTE The reverberation characteristics of the test room may exert a significant influence on the decay of the

acoustic test signal.
4.7 Signal level control
4.7.1 Step size
The signal level shall be variable in intervals of 5 dB or less.
4.7.2 Accuracy

The maximum accumulated error in the difference between any two signal level settings over the total signal

level range of the attenuator shall not exceed 3 dB, as measured acoustically at the reference point. In

addition, the specifications given in IEC 60645-1 shall be complied with.
4.7.3 Dynamic range

In the frequency range 500 Hz to 6 000 Hz, the test signal hearing level at the reference point shall cover at

least the range 0 dB to 80 dB.

NOTE It is desirable that the same test signal hearing level range be covered outside this frequency range.

4.8 Means and scales for calibration

The equipment shall provide means for adjusting the level of each test sound separately. The scale shall be

expressed in hearing level or sound pressure level. Measurements shall be made with a sound level meter

conforming to IEC 61672-1, type 1.

For pure tones and one-third-octave bands of noise in a frontally incident field, and for one-third-octave bands

of noise in a diffuse sound field, reference threshold sound pressure levels corresponding to the normal

binaural threshold of hearing as specified in ISO 226 shall be taken as reference threshold sound pressure

levels. These data shall be used also for FM tones complying with the requirements of 4.3. For other

combinations of test signal and sound field type, no standardized data exist.

NOTE 1 In practice, other angles of incidence are also used, e.g. 45°. No standardized reference threshold sound

pressure levels presently exist. However, in Annex B, correction values for 45° and 90° angles of incidence are given.

© ISO 2009 – All rights reserved 5
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SIST EN ISO 8253-2:2010
ISO 8253-2:2009(E)

NOTE 2 lt is recognized that, in applications where only the differences in thresholds of hearing between two listening

conditions are to be determined (e.g. with/without hearing aid), relative values of the test sound pressure level can suffice.

5 Sound field characteristics
5.1 General

The environment in which sound field audiometry is undertaken can vary considerably. Three types are

specified that allow a suitable sound field to be established in most situations in practice. Two wel

...

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