SIST EN ISO 8253-1:2011

SLOVENSKI STANDARD
01-marec-2011
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SIST EN 26189:1999
SIST EN ISO 8253-1:1999
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Acoustics - Audiometric test methods - Part 1: Pure-tone air and bone conduction
audiometry (ISO 8253-1:2010)
Akustik - Audiometrische Prüfverfahren - Teil 1: Grundlegende Verfahren der Luft- und
Knochenleitungs-Schwellenaudiometrie mit reinen Tönen (ISO 8253-1:2010)
Acoustique - Méthodes d'essais audiométriques - Partie 1: Audiométrie à sons purs en
conduction aérienne et en conduction osseuse (ISO 8253-1:2010)
Ta slovenski standard je istoveten z: EN ISO 8253-1:2010
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
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 8253-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
November 2010
ICS 13.140 Supersedes EN 26189:1991, EN ISO 8253-1:1998
English Version
Acoustics - Audiometric test methods - Part 1: Pure-tone air and
bone conduction audiometry (ISO 8253-1:2010)
Acoustique - Méthodes d'essais audiométriques - Partie 1: Akustik - Audiometrische Prüfverfahren - Teil 1:
Audiométrie à sons purs en conduction aérienne et en Grundlegende Verfahren der Luft- und Knochenleitungs-
conduction osseuse (ISO 8253-1:2010) Schwellenaudiometrie mit reinen Tönen (ISO 8253-1:2010)
This European Standard was approved by CEN on 25 September 2010.

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-CENELEC 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-CENELEC Management Centre has the same
status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, 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
© 2010 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 8253-1:2010: E
worldwide for CEN national Members.

Contents Page
Foreword .3

Foreword
This document (EN ISO 8253-1:2010) has been prepared by Technical Committee ISO/TC 43 “Acoustics” in
collaboration with 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 May 2011, and conflicting national standards shall be withdrawn at the
latest by May 2011.
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 26189:1991 and EN ISO 8253-1:1998.
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, Croatia, 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 8253-1:2010 has been approved by CEN as a EN ISO 8253-1:2010 without any modification.

INTERNATIONAL ISO
STANDARD 8253-1
Second edition
2010-11-01
Acoustics — Audiometric test methods —
Part 1:
Pure-tone air and bone conduction
audiometry
Acoustique — Méthodes d'essais audiométriques —
Partie 1: Audiométrie à sons purs en conduction aérienne et en
conduction osseuse
Reference number
ISO 8253-1:2010(E)
©
ISO 2010
ISO 8253-1:2010(E)
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Published in Switzerland
ii © ISO 2010 – All rights reserved

ISO 8253-1:2010(E)
Contents Page
Foreword .v
Introduction.vi
1 Scope.1
2 Normative references.1
3 Terms and definitions .2
4 General aspects of audiometric measurements .4
4.1 General .4
4.2 Standard reference zero for the calibration of audiometric equipment .5
4.3 Requirements on audiometric equipment .5
4.4 Qualified tester .5
4.5 Test time.5
4.6 Conditions for audiometric test environments .5
4.7 Measurement uncertainty.6
5 Preparation and instruction of test subjects before audiometric testing and positioning of
transducers .6
5.1 Preparation of test subjects .6
5.2 Instruction of test subjects.7
5.3 Placement of transducers .7
6 Air conduction hearing threshold level determinations using fixed-frequency audiometry .7
6.1 General .7
6.2 Manually controlled threshold determination .8
6.3 Hearing threshold determination with an automatic recording audiometer.10
6.4 Computer-controlled threshold determination.12
7 Air conduction hearing threshold level determinations using sweep-frequency
audiometry .12
7.1 General .12
7.2 Presentation of test tone .12
7.3 Familiarization .12
7.4 Hearing threshold level measurement .12
7.5 Calculation of hearing threshold level at a specified frequency.12
8 Bone conduction hearing threshold audiometry .13
8.1 Method of audiometry.13
8.2 Occlusion .13
8.3 Airborne sound radiation from the bone vibrator.13
8.4 Vibrotactile sensation .13
8.5 Procedures for testing with masking in bone conduction audiometry .13
9 Screening audiometry.14
9.1 General .14
9.2 Procedure for the screening test .14
10 Audiograms.15
11 Permissible ambient noise .16
11.1 Permissible ambient noise for threshold determinations.16
11.2 Psycho-acoustic check on ambient noise.16
12 Maintenance and calibration of audiometric equipment.20
12.1 General .20
12.2 Intervals between checks .20
ISO 8253-1:2010(E)
12.3 Stage A — Routine checking and subjective tests . 20
12.4 Stage B — Periodic objective checks. 21
12.5 Stage C — Basic calibration tests. 22
Annex A (informative) Measurement uncertainty . 23
Bibliography. 28

iv © ISO 2010 – All rights reserved

ISO 8253-1:2010(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 8253-1 was prepared by Technical Committee ISO/TC 43, Acoustics.
This second edition cancels and replaces the first edition (ISO 8253-1:1989) and ISO 6189:1983, which have
been technically revised.
ISO 8253 consists of the following parts, under the general title Acoustics — Audiometric test methods:
⎯ Part 1: Pure-tone air and bone conduction audiometry
⎯ Part 2: Sound field audiometry with pure-tone and narrow-band test signals
⎯ Part 3: Speech audiometry
ISO 8253-1:2010(E)
Introduction
This International Standard specifies requirements and procedures for carrying out basic audiometric tests in
which pure tones are presented to the test subject using earphones or bone vibrators. Electrophysiological
test methods are not included.
In order to obtain a reliable measure of hearing ability, many factors are involved. IEC 60645-1 specifies
requirements for audiometers. It is essential that audiometric equipment, when in service, be checked and the
calibration maintained. This part of ISO 8253 outlines a calibration scheme. To avoid masking of the test
signal by ambient noise in the audiometric test room, the levels of the ambient noise shall not exceed certain
values, depending upon the method of signal presentation to the test subject, i.e. by different earphones or by
bone vibrator. This part of ISO 8253 gives maximum permissible ambient sound pressure levels which shall
not be exceeded when hearing threshold levels down to 0 dB have to be measured. It indicates the maximum
ambient sound pressure levels which are permissible when other minimum hearing threshold levels require
measurement. It sets out procedures for determining hearing threshold levels by pure-tone air conduction and
bone conduction audiometry. For screening purposes, only methods for air conduction audiometry are
outlined.
Audiometry can be performed by using:
a) a manual audiometer;
b) an automatic recording audiometer;
c) computer-controlled audiometric equipment.
Methods for threshold audiometry are given for these three types of signal presentation. For screening
purposes, only methods using a manual or a computer-controlled audiometer are set out. The procedures are
applicable to the majority of adults and children. Other procedures may yield results equivalent to those
derived by the procedures specified in this part of ISO 8253. For very young, aged or sick people, some
modification of the recommended procedures is likely to be required. This may result in a less accurate
measurement of hearing.
vi © ISO 2010 – All rights reserved

INTERNATIONAL STANDARD ISO 8253-1:2010(E)

Acoustics — Audiometric test methods —
Part 1:
Pure-tone air and bone conduction audiometry
1 Scope
This part of ISO 8253 specifies procedures and requirements for pure-tone air conduction and bone
conduction threshold audiometry. For screening purposes, only pure-tone air conduction audiometric test
methods are specified. It is possible that the procedures are not appropriate for special populations, e.g. very
young children.
This part of ISO 8253 does not cover audiometric procedures to be carried out at levels above the hearing
threshold levels of the subjects.
Procedures and requirements for speech audiometry, electrophysiological audiometry, and where
loudspeakers are used as a sound source are not specified.
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 389-1, Acoustics — Reference zero for the calibration of audiometric equipment — Part 1: Reference
equivalent threshold sound pressure levels for pure tones and supra-aural earphones
ISO 389-2, Acoustics — Reference zero for the calibration of audiometric equipment — Part 2: Reference
equivalent threshold sound pressure levels for pure tones and insert earphones
ISO 389-3:1994, Acoustics — Reference zero for the calibration of audiometric equipment — Part 3:
Reference equivalent threshold force levels for pure tones and bone vibrators
ISO 389-5, Acoustics — Reference zero for the calibration of audiometric equipment — Part 5: Reference
equivalent threshold sound pressure levels for pure tones in the frequency range 8 kHz to 16 kHz
ISO 389-8, Acoustics — Reference zero for the calibration of audiometric equipment — Part 8: Reference
equivalent threshold sound pressure levels for pure tones and circumaural earphones
IEC 60645-1:2001, Electroacoustics — Audiological equipment — Part 1: Pure-tone audiometers
IEC 61260, Electroacoustics — Octave-band and fractional-octave-band filters
IEC 61672-1, Electroacoustics — Sound level meters — Part 1: Specifications
ISO/IEC Guide 98-3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in
measurement (GUM:1995)
ISO 8253-1:2010(E)
3 Terms and definitions
For the purposes of this part of ISO 8253, the following definitions apply.
3.1
air conduction
transmission of sound through the external and middle ear to the inner ear
3.2
ear simulator
device for measuring the acoustic output of sound sources where the sound pressure is measured by a
calibrated microphone coupled to the source so that the overall acoustic impedance of the device
approximates that of the normal human ear at a given location and in a given frequency band
[4] [6]
NOTE An ear simulator is specified in IEC 60318-1 and IEC 60318-4 .
3.3
acoustic coupler
device for measuring the acoustic output of sound sources where the sound pressure is measured by a
calibrated microphone coupled to the source by a cavity of predetermined shape and volume which does not
necessarily approximate the acoustic impedance of the normal human ear
[5] [7]
NOTE An acoustic coupler is specified in IEC 60318-3 and IEC 60318-5 .
3.4
bone conduction
transmission of sound to the inner ear primarily by means of mechanical vibration of the cranial bones
3.5
bone vibrator
electromechanical transducer intended to produce the sensation of hearing by vibrating the cranial bones
3.6
mechanical coupler
device designed to present a specified mechanical impedance to a vibrator applied with a specified static
force and equipped with a mechano-electrical transducer to measure the vibratory force level at the surface of
contact between vibrator and mechanical coupler
[8]
NOTE A mechanical coupler is specified in IEC 60318-6 .
3.7
otologically normal person
person in a normal state of health who is free from all signs and 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 familial hearing loss
3.8
hearing threshold
lowest sound pressure level or vibratory force level at which, under specified conditions, a person gives a
predetermined percentage of correct detection responses on repeated trials
3.9
equivalent threshold sound pressure level
for a given ear, at a specified frequency, for a specified type of earphone and for a stated force of application
of the earphone to the human ear, the sound pressure level set up by the earphone in a specified acoustic
coupler or ear simulator when the earphone is actuated by that voltage which, with the earphone applied to
the ear concerned, would correspond to the hearing threshold
2 © ISO 2010 – All rights reserved

ISO 8253-1:2010(E)
3.10
reference equivalent threshold sound pressure level
RETSPL
at a specified frequency, the median value of the equivalent threshold sound pressure levels of a sufficiently
large number of ears of otologically normal persons of both sexes aged from 18 years to 25 years inclusive,
expressing the hearing threshold in a specified acoustic coupler or ear simulator for a specified type of
earphone
NOTE ISO 389-1 refers to an age range of 18 years to 30 years inclusive, and specifies modal values.
3.11
equivalent threshold vibratory force level
for a given ear, at a specified frequency, for a specified configuration of bone vibrator and for a stated force of
application of the bone vibrator to the human mastoid or forehead, the vibratory force level set up by the bone
vibrator on a specified mechanical coupler when the bone vibrator is actuated by that voltage which, with the
bone vibrator applied to the mastoid or forehead concerned, would correspond to the hearing threshold
3.12
reference equivalent threshold vibratory force level
RETVFL
at a specified frequency, the median value of the equivalent threshold vibratory force levels of a sufficiently
large number of ears of otologically normal persons of both sexes aged from 18 years to 25 years inclusive,
expressing the hearing threshold in a specified mechanical coupler for a specified type of bone vibrator
NOTE ISO 389-3 refers to an age range of 18 years to 30 years inclusive, and specifies an arithmetic mean.
3.13
hearing level of a pure tone
HL of a pure tone
at a specified frequency, for a specific type of transducer and for a specified manner of application, sound
pressure level or vibratory force level of a pure tone, produced by a transducer in a specific ear simulator or
mechanical coupler, minus the appropriate reference equivalent threshold sound pressure level or reference
equivalent threshold vibratory force level
3.14
hearing threshold level of a given ear
at a specified frequency and for a specific type of transducer, hearing threshold at that frequency, expressed
as hearing level
3.15
occlusion effect
change (usually an increase) in level of a bone-conducted signal reaching the inner ear when an earphone or
an earplug is placed over or at the entrance of the ear canal, thereby forming an enclosed air volume in the
external ear
NOTE The effect is greatest at low frequencies.
3.16
masking
process by which the hearing threshold of a given ear for a particular sound is raised by the presence of
another (masking) sound
3.17
effective masking level of a noise band
level equal to that hearing level of a pure tone, the frequency of which coincides with the geometric centre
frequency of the noise band, to which the threshold of hearing of the pure tone is raised by the presence of
the masking noise band
NOTE IEC 60645-1:2001, 8.5.2 a), specifies that masking levels for narrow-band noise be calibrated in terms of
effective masking level.
ISO 8253-1:2010(E)
3.18
vibrotactile threshold level
level of the vibratory force or sound pressure at which a person gives 50 % of correct detection responses on
repeated trials due to the sensation of vibration on the skin
3.19
pure-tone audiometer
electroacoustic instrument, equipped with earphone(s), that provides pure tones of specified frequencies at
known sound pressure levels
NOTE In addition, it may be equipped with bone vibrator(s) and/or masking facilities.
3.20
manual audiometer
audiometer in which the signal presentations, frequency and hearing level selection and recording of the
results are performed manually
3.21
automatic-recording audiometer
audiometer in which signal presentations, hearing level variation, frequency selection or frequency variation,
and recording of the responses of the test subject are implemented automatically
NOTE Hearing level change is under the control of the test subject and is recorded automatically.
3.22
automatic fixed-frequency audiometry
audiometry in which hearing level variations are under the control of the test subject and are recorded
automatically for specific frequencies
3.23
automatic sweep-frequency audiometry
audiometry in which hearing level variations are under the control of the test subject and where the frequency
is varied continuously or in steps much smaller than one-third octave
3.24
screening audiometry
pass-fail procedure where pure tones of a fixed level, the screening level, are presented
3.25
audiogram
presentation, in graphical or tabular form, of the hearing threshold levels of the ears of the test subject,
determined under specified conditions and by a specified method, as a function of frequency
4 General aspects of audiometric measurements
4.1 General
Hearing threshold levels can be determined by air conduction and bone conduction audiometry. In air
conduction audiometry, the test signal is presented to the test subject by earphones. In bone conduction
audiometry, the test signal is presented by a bone vibrator placed on the mastoid or forehead of the test
subject. It is recommended that threshold level determinations be started with air conduction measurements
followed by bone conduction measurements. Hearing threshold levels can be determined using test tones with
fixed frequencies (fixed-frequency audiometry) or a test signal with frequency varying with time according to a
predetermined rate of change (sweep-frequency audiometry). Methods for fixed-frequency audiometry are
given in Clause 6 and sweep-frequency audiometry is described in Clause 7. In air and bone conduction
measurements, the hearing threshold levels of both ears shall be determined separately. Under specified
conditions, masking noise shall be applied to the ear not under test (contralateral ear). The masking noise is
presented to that ear through a supra-aural, circumaural or insert-type earphone.
4 © ISO 2010 – All rights reserved

ISO 8253-1:2010(E)
4.2 Standard reference zero for the calibration of audiometric equipment
The standard reference zero for air conduction audiometers is given in ISO 389-1, ISO 389-2, ISO 389-5, and
ISO 389-8 and for bone conduction audiometers in ISO 389-3 in terms of reference equivalent threshold
sound pressure levels or vibratory force levels (RETSPL or RETVFL, respectively) at specified frequencies.
Different RETVFL values are valid for different locations of the vibrator, i.e. at the mastoid or forehead.
ISO 389-3:1994 presents values for mastoid location and its Annex C gives corresponding difference values
for forehead location of the vibrator.
4.3 Requirements on audiometric equipment
Audiometers shall be constructed in accordance with IEC 60645-1 and calibrated in accordance with the
requirements of the relevant part of ISO 389. In occupational audiometry and for testing of schoolchildren, a
type 4 audiometer (IEC 60645-1:2001) may be used and the frequency range sometimes limited to 500 Hz
and upwards.
4.4 Qualified tester
A qualified tester is understood to be someone who has followed an appropriate course of instruction in the
theory and practice of audiometric testing. This qualification may be specified by national authorities or other
suitable organizations. Throughout this part of ISO 8253, it is assumed that tests are carried out only by, or
under the supervision of, a qualified tester.
The tester should make decisions on the following aspects of the audiometric test which are not specified in
detail in this part of ISO 8253, namely whether:
a) the left or the right ear is tested first (usually the ear considered to be more sensitive is chosen);
b) masking is required;
c) responses of the test subject correspond to the test signals;
d) there is any external noise event or any behaviour response of the test subject that might invalidate the
test;
e) to interrupt, terminate or repeat all or part of the test.
4.5 Test time
Care shall be taken not to fatigue the test subject unduly since reliable results may be progressively difficult to
obtain if the test subject is not given a rest from testing after about 20 min.
4.6 Conditions for audiometric test environments
Ambient sound pressure levels in an audiometric test room shall not exceed the values specified in Clause 11.
The test subject and the tester shall be comfortably seated during audiometric testing and shall be neither
disturbed nor distracted by unrelated events nor by people in the vicinity.
Air temperature in the audiometric test room should be in the range permitted for offices by local authorities.
The audiometric test room should allow for sufficient exchange of air.
If the audiometer is operated manually, the test subject shall be clearly visible to the tester who shall,
however, not be able to see the audiometer settings change nor the test tone being switched on or
interrupted. When using an automatic recording audiometer, the recording mechanism shall not be visible to
the test subject.
ISO 8253-1:2010(E)
When the test is carried out from outside the audiometric test room, the test subject shall be visually
monitored through a window or by a closed-circuit TV system. Acoustic monitoring of the subject should be
undertaken.
4.7 Measurement uncertainty
The uncertainty of hearing threshold levels determined in accordance with any of the procedures specified in
this part of ISO 8253 depends on a variety of parameters, such as:
a) the performance of the audiometric equipment used;
b) the type of transducers used and their fitting by the tester;
c) the frequency of test tones;
d) the conditions of the test environment, especially the ambient noise;
e) the qualification and experience of the tester;
f) the cooperation of the test subject and the reliability of responses;
g) the use of non-optimized masking noise.
Due to the complexity of the measurement process, including the personal behaviour of both the test subject
and the tester, it is difficult to express the measurement uncertainty in a single generally valid figure. However,
a detailed evaluation of measurement uncertainty provides useful information on the reliability of audiometric
test results and provides a sufficient estimate of the uncertainty in most applications.
The uncertainty of results of measurements according to this part of ISO 8253 shall be evaluated in
accordance with ISO/IEC Guide 98-3. If reported, the expanded uncertainty together with the corresponding
coverage factor for a stated coverage probability, as defined in ISO/IEC Guide 98-3, shall be given. Guidance
on the determination of the expanded uncertainty is given in Annex A.
5 Preparation and instruction of test subjects before audiometric testing and
positioning of transducers
5.1 Preparation of test subjects
Recent exposure to noise may cause a temporary elevation of the hearing threshold levels. Therefore,
significant noise exposure should be avoided before audiometric testing or it shall be noted. In order to avoid
errors due to excessive physical exertion, test subjects should be present at least 5 min prior to testing.
Normally, the audiometric test is preceded by an otoscopic examination carried out by a qualified person. If
obstructing wax is found in the canal(s) of the outer ear it shall be removed and audiometry may be delayed
for a suitable period. The ear should also be checked for the possibility of collapsing ear canals and
appropriate action taken, if necessary.
NOTE 1 Preliminary information about the type of hearing loss and masking requirements can be obtained by
performing tuning fork tests.
NOTE 2 The qualifications of a person can be specified by national authorities or other suitable organizations. The
qualified person need not be the same person as the qualified tester mentioned in 4.4.
6 © ISO 2010 – All rights reserved

ISO 8253-1:2010(E)
5.2 Instruction of test subjects
In order to achieve reliable test results, it is essential that relevant instruction in the test procedure be given
unambiguously and that it is fully understood by the test subject.
The instructions shall be phrased in language appropriate to the listener and shall normally indicate:
a) the response task;
b) the need to respond whenever the tone is heard in either ear, no matter how faint it may be;
c) the need to respond as soon as the tone is heard and to stop responding immediately once the tone is no
longer heard;
d) the general pitch sequence of the tones;
e) the ear to be tested first.
The response from the test subject indicating when the tone is heard and when it is no longer heard shall be
clearly observable. Examples of commonly used responses are:
⎯ pressing and releasing a signal switch;
⎯ raising and lowering the finger or hand.
Test subjects shall also be instructed to avoid unnecessary movements so as to obviate extraneous noise.
After the instructions have been given, the test subject shall be asked if he or she has understood. The test
subject shall be informed that he or she may interrupt the test in the case of discomfort. If there is any doubt,
the instructions should be repeated.
5.3 Placement of transducers
In advance of testing, the following actions should be undertaken: spectacles and head ornaments, when
necessary, and hearing aids shall be removed. Hair shall be moved from between the head and the sound
transducers, i.e. earphones and bone vibrators, if possible. The transducers shall be fitted by the tester to
ensure that they are properly positioned and subjects shall be instructed not to touch the transducers
thereafter. The sound opening of an earphone shall face the ear canal entrance. The bone vibrator shall be
positioned so that the largest possible area of the tip is in contact with the skull. If placed on the mastoid, the
vibrator shall be positioned behind and as near as possible to the pinna, without touching it.
6 Air conduction hearing threshold level determinations using fixed-frequency
audiometry
6.1 General
The audiometric test may be carried out using a manual audiometer or an automatic-recording audiometer.
The procedures are specified in 6.2, 6.3, and 6.4.
The order of presentation of test tones when the audiometer settings are performed manually shall be from
1 000 Hz upwards, followed by the lower frequency range, in descending order. A repeat test shall be carried
out at 1 000 Hz on the ear tested first.
Vibrotactile sensations may occur at low frequencies and high hearing levels; care, therefore, shall be taken
that such sensations are not misinterpreted as hearing sensations.
Preferably, automatic-recording audiometers should present test tones in the same sequence as in manual
audiometry.
ISO 8253-1:2010(E)
6.2 Manually controlled threshold determination
6.2.1 Presentation and interruption of test tones
The test tone shall be continuous and presented for a duration of 1 s to 2 s. When a response occurs, the
interval between tone presentations shall be varied but shall not be shorter than the test tone duration. Unless
otherwise stated, reference to tone presentation throughout this part of ISO 8253 refers to this method.
Automatically pulsed tones are sometimes used as an alternative stimulus. However, correlative data are not
currently available. The use of such stimuli should be noted on the audiogram.
6.2.2 Initial familiarization
The test subject shall be familiarized with the task prior to threshold determination by presenting a signal of
sufficient intensity to evoke a definite response. By using the familiarization step, the tester can be sure that
the test subject understands and can perform the response task.
EXAMPLE The following method of familiarization can be used:
a) present a tone of 1 000 Hz at a hearing level which is clearly audible, e.g. 40 dB for a normal hearing test subject;
b) reduce the level of the tone in steps of 20 dB until no response occurs;
c) increase the level of the tone in steps of 10 dB until a response occurs;
d) present the tone again at the same level.
If the responses are consistent with the tone presentation, the familiarization is complete. If not, it should be repeated.
After a second failure, the instructions should be repeated.
In cases of profound deafness, these procedures may not be applicable.
6.2.3 Hearing threshold measurements with and without masking
6.2.3.1 General
In 6.2.3.2, test procedures are outlined for those tests in which masking noise is not applied to the non-test
ear. In 6.2.3.3, procedures are outlined for tests with masking. The method for calculating hearing threshold
level is given in 6.2.4.
6.2.3.2 Procedures for testing without masking
Two audiometric test procedures with a manual audiometer are specified: a bracketing method and an
ascending method. These methods differ only in the sequence of the levels of the test tones presented to the
test subject.
In the ascending method, consecutive test tones having ascending levels are presented until a response
occurs.
In the bracketing method, consecutive test tones having ascending levels are presented until a response
occurs, after which test tones having levels in a descending sequence are presented.
When properly carried out, both methods result in substantially the same hearing threshold levels.
Measurements using the ascending method differ from those of the bracketing method only in step 2 of the
measurements presented below.
8 © ISO 2010 – All rights reserved

ISO 8253-1:2010(E)
If the hearing threshold level measurements result in a hearing level of 40 dB or more in either ear at any
frequency, these results should be interpreted with caution due to the phenomenon of cross-hearing.
Contralateral masking can then be necessary.
Step 1
Present the first test tone at a level which is 10 dB below the lowest level of the response of the test subject
during the familiarization session. After each failure to respond to a test tone, increase the level of the test
tone in steps of 5 dB until a response occurs.
Step 2
Ascending method
After the response, decrease the level in steps of 10 dB until no response occurs. Then begin another ascent
with 5 dB steps. Continue until three responses occur at the same level out of a maximum of five ascents.
This level is then defined as the hearing threshold level (see 6.2.4.2).
If less than three responses out of five ascents have been obtained at the same level, present a test tone at a
level 10 dB higher than the level of the last response. Then repeat the general test procedure: 10 dB down
after a response, 5 dB up until a response occurs.
A shortened version of the ascending method has been shown to yield nearly equivalent results and may be
appropriate in some cases. In this shortened version, continue the testing until at least two responses occur at
the same level out of three ascents.
Bracketing method
After the response, increase the level of the test tone by 5 dB and begin a descent in which the level of the
tone is decreased in steps of 5 dB until no response occurs. Then decrease the level of the test tone another
5 dB and begin the next ascent at this level. This should be continued until three ascents and three descents
have been completed.
Shortened versions of the bracketing method may be appropriate in some cases. Shortening consists of
omitting the further descent of 5 dB after no response occurs or requiring only two ascents and two descents
in series provided that the four minimal response levels differ by no more than 5 dB.
Step 3
Proceed to the next test frequency at an estimated audible level, as indicated by the previous responses, and
repeat step 2. Finish all test frequencies on one ear.
NOTE For any frequency, the familiarization, or an abbreviated form of it, can be repeated.
Finally, repeat the measurement at 1 000 Hz. If the results at 1 000 Hz of the repeat measurement for that ear
agree to 5 dB or less with those of the first measurements for the same ear, proceed to the other ear. If 10 dB
or more improvement or worsening in hearing threshold level is discernible, retest at further frequencies in the
same order until agreement to 5 dB or less has been obtained.
Step 4
Proceed until both ears have been tested.
6.2.3.3 Procedures for testing with masking
To avoid the test tone bein
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