SIST EN ISO 8253-1:1999

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Akustik - Audiometrische Prüfverfahren - Teil 1: Grundlegende Verfahren der Luft- und Knochenleitungs-Schwellenaudiometrie mit reinen Tönen (ISO 8253-1:1989)Acoustique - Méthodes d'essais audiométriques - Partie 1: Audiométrie liminaire fondamentale a sons purs en conduction aérienne et en conduction osseuse (ISO 8253-1:1989)Acoustics - Audiometric test methods - Part 1: Basic pure tone air and bone conduction threshold audiometry (ISO 8253-1:1989)17.140.01Acoustic measurements and noise abatement in general13.140Vpliv hrupa na ljudiNoise with respect to human beingsICS:Ta slovenski standard je istoveten z:EN ISO 8253-1:1998SIST EN ISO 8253-1:1999en01-november-1999SIST EN ISO 8253-1:1999SLOVENSKI
STANDARD



SIST EN ISO 8253-1:1999



SIST EN ISO 8253-1:1999



SIST EN ISO 8253-1:1999



SIST EN ISO 8253-1:1999



SIST EN ISO 8253-1:1999



INTERNATIONAL STANDARD IS0 8253-l First edition 1989-11-15 Acoustics - Audiometric test methods - Part I: Basic pure tone air and bone conduction threshold audiometry Acoustique - Mkhodes d’essais audiome’triques - Partie 7 : Audiomhtrie liminaire fondamen tale ;5 sons purs en conduction akienne et en conduction osseuse Reference number IS0 8253-l : 1989 (E) SIST EN ISO 8253-1:1999



1s0 8253-l : 1989 (El Foreword IS0 (the International Organization for Standardization) is a worldwide federation of national standards bodies (IS0 member bodies). The work of preparing International Standards is normally carried out through IS0 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, govern- mental and non-governmental, in liaison with ISO, also take part in the work. IS0 collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the IS0 Council. They are approved in accordance with IS0 procedures requiring at least 75 % approval by the member bodies voting. International Standard IS0 8253-l was prepared by Technical Committee ISO/TC 43, Acoustics. IS0 8253 will consist of the following parts, under the general title Acoustics - Audio- metric test methods: - - Part I: Basic pure tone air and bone conduction threshold audiometry Part 2: Sound field audiometry with pure tone and narrow-band signals Annex A of this part of IS0 8253 is for information only. 0 IS0 1989 All rights reserved. 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 the publisher. International Organization for Standardization . Case postale 56 l CH-1211 Geneve 20 l Switzerland Printed in Switzerland ii SIST EN ISO 8253-1:1999



ISO8253-1 :1989 E) Introduction This International Standard lays down 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. Pro- cedures for air conduction threshold audiometry for hearing conservation purposes are given in IS0 6189. Where appropriate, both International Standards have been brought into line with one another. In order to obtain a reliable measure of hearing ability, many factors are involved. IEC 645 specifies requirements for audiometers. It is essential that audiometric equip- ment, when in service, be checked and the calibration maintained. This part of IS0 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 cer- tain values, depending upon the method of signal presentation to the test subject, i.e. by earphone or by bone vibrator. This part of IS0 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 have to be measured. 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 presenta- tion. 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 IS0 8253. For very young, aged or sick people, some modification of the recom- mended procedures is likely to be required. This may result in a less accurate measure- ment of hearing. SIST EN ISO 8253-1:1999



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INTERNATIONAL STANDARD IS0 8253-l : 1989 (E) Acoustics - Audiometric test methods - Part 1: Basic pure tone air and bone conduction threshold audiometry 1 Scope This part of IS0 8253 specifies procedures and requirements for air conduction and bone conduction threshold audiometry. For screening purposes, only air conduction pure tone audiometric test methods are described. The procedures may not be ap- propriate for special populations, for example very young children. Some audiometric procedures need to be carried out at levels above the hearing threshold levels of the subjects. These and other tests are not described in this part of IS0 8253. Procedures and requirements for speech audiometry, elec- trophysiological audiometry, and where loudspeakers are used as a sound source are not specified. Air conduction threshold audiometry for hearing conservation purposes is described in IS0 6189. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this part of IS0 8253. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this part of IS0 8253 are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and IS0 maintain registers of currently valid International Standards. IS0 389 : 1985, Acoustics - Standard reference zero for the calibration of pure tone air conduction audiometers. IS0 7566 : 1987, Acoustics - Standard reference zero for the calibration of pure- tone bone conduction audiometers. IEC 225 : 1966, Octave, half-octave and third-octave band filters intended for the analysis of sounds and vibrations. IEC 303 : 1970, IEC provisional reference coupler for the calibra- tion of earphones used in audiometry. IEC 318 : 1970, An IEC artificial ear, of the wideband type, for the calibration of earphones used in audiometry. I EC 373 : I971, An IEC mechanical coupler for the calibration of bone vibrators having a specified contact area and being applied with a specified static force. I EC 645 : 1979, Audiometers. IEC 651 : 1979, Sound level meters. I EC 804 : I985, Integrating-averaging sound level meters. 3 Definitions For the purposes of this part of IS0 8253, the following defini- tions apply. 3.1 air conduction: The transmission of sound through the outer and middle ear to the inner ear. 3.2 acoustic coupler: A cavity of specified shape and volume which is used for the calibration of an earphone in con- junction with a calibrated microphone to measure the sound pressure developed within the cavity. NOTE - An acoustic coupler is specified in IEC 303. 3.3 artificial ear: A device for the calibration of an earphone which presents to the earphone an acoustic impedance equivalent to the impedance presented by the average human ear. It is equipped with a calibrated microphone for the measurement of the sound pressure developed by the ear- phone. NOTE - An artificial ear is specified in IEC 318. 3.4 bone conduction: The transmission of sound to the inner ear primarily by means of mechanical vibration of the cranial bones. 3.5 bone vibrator: An electromechanical transducer in- tended to produce the sensation of hearing by vibrating the cranial bones. 1 SIST EN ISO 8253-1:1999



IS0 8253-l : 1989 (EI 36 mechanical coupler: A device designed to present a sbecified 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. NOTE - A mechanical coupler is specified in IEC 373. 3.7 otologically normal person: A 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. 3.8 hearing threshold: The lowest sound pressure level or vibratory force level at which, under specified conditions, a per- son gives a predetermined percentage of correct detection responses on repeated trials. 3.9 equivalent threshold sound pressure level (monaural earphone listening): 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 artificial ear when the earphone is actuated by that voltage which, with the earphone applied to the ear concerned, would correspond to the hearing threshold. 3.10 reference equivalent threshold sound pressure level (RETSPL): At a specified frequency, the modal value of the equivalent threshold sound pressure levels of a sufficiently large number of ears of otologically normal persons of both sexes aged between I8 years and 30 years inclusive, expressing the hearing threshold in a specified acoustic coupler or artificial ear for a specified type of earphone. 3.11 equivalent threshold force level (monaural listening): 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 bone, the vibratory force level set up by the bone vibrator on a specified mechanical coupler when the bone vibrator is ac- tuated by that voltage which, with the bone vibrator applied to the mastoid bone concerned, would correspond to the hearing threshold. 3.12 reference equivalent threshold force level (RETFL) : At a specified frequency, the mean value of the equivalent threshold force levels of a sufficiently large number of ears of otologically normal persons of both sexes aged between I8 years and 30 years inclusive, expressing the hearing threshold in a specified mechanical coupler for a specified type of bone vibrator. 3.13 hearing level of a pure tone (at a specified frequency, for a specific type of transducer and for a specified manner of application): The sound pressure level (or the vibratory force level) of a pure tone, produced by the transducer in a specified artificial ear or acoustic coupler (or mechanical coupler) minus the appropriate reference equivalent threshold sound pressure level (or reference equivalent threshold force level). 3.14 hearing threshold level of a given ear (at a specified frequency and for a specified type of transducer): The hearing threshold at that frequency, expressed as hearing level. 3.15 occlusion effect: The 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. The effect is greatest at low frequencies. 3.16 masking : (I) The process by which the hearing threshold of a given ear to a particular sound is raised by the presence of another (masking) sound. (2) The amount by which the hearing threshold level of a given ear is so raised, expressed in decibels. 3.17 effective masking level of a noise band: A 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 645 specifies that masking levels for be calibrated in terms of effective masking level. narrow band noise 3.18 vibrotactile threshold level: The level of the vibratory force or sound pressure at which a person gives a predeter- mined percentage of correct detection responses on repeated trials due to the sensation of vibration on the skin. 3.19 pure-tone audiometer: An electroacoustic instru- ment, equipped with earphones, that provides pure tones of specified frequencies at known sound pressure levels. In addi- tion, it may be equipped with bone vibrator(s) and/or masking facilities. 3.20 manual audiometer: An audiometer in which the signal presentations, frequency and hearing level selection and recording of the results are performed manually. 3.21 computer-controlled audiometer: An audiometer in which the test procedure is controlled by computer. For the purposes of this part of IS0 8253, a computer is considered as any electronic device that has a program controlling the test procedure. 3.22 automatic recording audiometer: An audiometer in which hearing level variations are under the subject’s control and are recorded automatically. 3.23 sweep-frequency audiometer: An automatic re- cording audiometer where the frequency is varied continuously or in steps much smaller than one-third octave. 3.24 screening audiometry: Screening audiometry is a pass-fail procedure where pure tones of a fixed level, the screening level, are presented. SIST EN ISO 8253-1:1999



IS0 8253-1 : 1989 (E) 3.25 pure-tone audiogram of a subject: Presentation, in graphical or tabular form, of the hearing threshold levels of the subject’s ears, determined under specified conditions and by a specified method, as a function of frequency. 4 m General aspects of audio metric easurements 4.1 General Hearing threshold levels can be determined by air conduction and bone conduction audiometry. In air conduction audio- metry, the test signal is presented to the test subject by ear- phones. 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 frequen- cies (fixed-frequency audiometry) or a test signal with frequen- cy 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 condi- tions, masking noise shall be applied to the ear not under test (contra-lateral ear). The masking noise is presented to that ear through a supra-aural, circum-aural or insert-type earphone. No calibration standards for insert or circum-aural earphones currently exist. 4.2 Standard reference zero for the calibration of audiometric equipment The standard reference zero for air conduction audiometers is given in IS0 389 and IS0 389/Add. 1 and Add. 2 and for bone conduction audiometers in IS0 7566 in terms of reference equivalent threshold sound pressure levels or force levels (RETSPL or RETFL respectively) at specifiedfrequencies. Dif- ferent RETFL-values are valid for different locations of the vibrator, i.e. at the mastoid or forehead. IS0 7566 : 1987 presents values for mastoid location and gives corresponding difference values for forehead location of the vibrator in annex C. 4.3 Requirements on audiometric equipment Audiometers shall be constructed in accordance with IEC 645 and calibrated in accordance with the requirements of IS0 389 and IS0 7566. 4.4 Qualified tester A qualified tester is understood to be someone who has fol- lowed 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 IS0 8253, it is assumed that tests will only be carried out by, or be under the supervision of, a qualified tester. NOTE - The tester should make decisions on the following aspects of the audiometric test which are not specified in detail in this part of IS0 8253: a) which sensitive) ; ear is tested first (usually the ear considered to be more b) whether or not masking is required; c) whether test signals; the responses of the test subject correspond with the d) whether there is any external noise event or any behaviour response of the test subject that might invalidate the test; or e) whether 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 presure levels in an audiometric not exceed the values specified in clause 11. test room shall The test subject and the tester shall be comfortably seated during audiometric testing and shall be neither disturbed nor distracted by non-related 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 audio- metric 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 but shall not be able to see the audiometer settings change nor the test tone switched on or interrupted. When using an automatic recording audiometer, the recording mechanism shall not be visible to the test subject. 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. 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 3 SIST EN ISO 8253-1:1999



Iso 8253-l : 1989 (E) 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. 6 Air conduction hearing threshold level determinations using fixed-frequency audiometry NOTES 6.1 General I Preliminary information about the type of hearing loss and masking requirements can be obtained by performing tuning fork tests. The audiometric test may be carried out using a manual audiometer, an automatic recording audiometer or a computer- controlled audiometer. The procedures are described in 6.2, 6.3 and 6.4. 2 The qualifications for a qualified person may tional authorities or other suitable organizations. be specified by na- 5.2 Instruction of test subjects 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 descen- ding order. A repeat test shall be carried out at 1 000 Hz on the ear tested first. In order to achieve reliable test results, it is essential that rele- vant instruction in the test procedure be given unambiguously and that it is fully understood by the test subject. The instructions shall be phrased in listener and shal I normal ly indicate language appropriate to the Vibrotactile sensations may occur at low frequencies and high hearing levels; care, therefore, shall be taken that such sensa- tions are not misinterpreted as hearing sensations. a) the response task; Preferably, automatic recording and computer controlled audiometers should present test tones in the same sequence as in manual audiometry. b) that the test su bject shall respo nd whenever the heard in either ear, no matter how faint it may be; tone is c) the need to respond as soon as the tone is heard and to stop responding immediately once the tone is no longer heard ; 6.2 Manually controlled threshold determination 6.2.1 Presentation and interruption of test tones d) the general pitch sequence of the sound; 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 IS0 8253 refers to this method. e) which ear shall be tested first. The response task from the test subject shall be clearly obser- vable to indicate when the tone is heard and is no longer heard. Examples of commonly used responses are a) pressing and releasing a signal switch; NOTE - Automatically pulsed tones are sometimes used as an alter- native stimulus. However, correlative data are not currently available. The use of such stimulus should be noted on the audiogram. b) 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/she has understood. The test subject shall be informed that he/she may interrupt the test in case of any discomfort. If there is any doubt, the instructions should be repeated. 6.2.2 Initial familiarization The test subject shall be familiarized with the task prior to threshold determination by presenting a signal of sufficient in- tensity 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. 5.3 Placement of transducers NOTE - The following method of familiarization can be used: In advance of testing, the following actions should be under- taken: spectacles and head ornaments, when necessary, and hearing aids shall be removed. Hair shall be moved from be- tween 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 sub- jects shall be instructed not to touch the transducers thereafter. Testing shall not commence immediately after the transducers have been positioned/adjusted. The sound opening of an ear- phone 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. a) present a tone of 1 000 Hz at a hearing level which is clearly audible, for example 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 IO 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 completed. If not, it should be repeated. After a second failure, the instructions should be repeated. 4 SIST EN ISO 8253-1:1999



ISo8253-1:1989 (E) In cases applicable. of profound deafness, these procedures may not be 6.2.3 Hearing threshold without masking level measurements with and In 6.2.3.1, test procedures are outlined for those tests in which masking noise is not applied to the non-test ear. In 6.2.3.2, pro- cedures are outlined for tests with masking. The method for calculating hearing threshold level is given in 6.2.4. 6.2.3.1 Procedures for testing without masking Two audiometric test procedures with a manual audiometer are specified : a bracketing 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 meth od, present consecutive ascending levels until a response occurs. test tones having In the bracketing method, present consecutive test tones having ascending levels until a response occurs, after which present test tones having levels in a descending sequence. When properly carried out, both methods tially the same hearing threshold levels. will result In substan- Measurements using the ascending method differ from those of the bracketing method only in step 2 of the measurements presented below. Step 1 Present the first test tone at a level which is 10 dB below the lowest level of the test subject’s response 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 and then begin another ascent. Continue until three responses occur at the same level out of a maximum of five ascents. If, using the ascending method, less than three responses out of five ascents (or less than two responses out of three ascents in the shortened method) 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 test procedure. A shortened version of the ascending method has been shown to yield nearly equivalent results and may be ap- propriate in some cases. In this shortened version, con- tinue 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. This consists of omitting the further descent of 5 dB after no response occurred 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. NOT E - For any frequency, form of it, may be repeated. the familiarization, or an abbreviated 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 im- provement 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. 6.2.3.2 Procedures for testing with masking To avoid the test tone being heard in the ear not under test, it may be necessary to apply masking noise to that ear. For the procedure described below, the masking noise signal is delivered by means of the supra-aural earphone. Although experience will, to a large extent, dictate the pro- cedures used and the choice of the masking noise level, the following procedure is recommended to determine the hearing threshold level with masking. Step 1 Present a test tone to the ear being tested at a level equal to the hearing threshold level without masking. Present mask- ing noise to the ear not under test with an effective masking level equal to the hearing threshold level of the ear not under test. Increase the level until the test tone is inaudible or until it exceeds the test tone level. Step 2 If the tone is still audible when the noise level equals the test tone level, assume this to be the hearing threshold level. If the tone is masked, increase its level until it becomes audible again. SIST EN ISO 8253-1:1999



IS0 8253-l : 1989 (El Step 3 6.3.1 Presentation of test tone Increase the noise level by 5 dB. If the test tone is inaudible, increase the test tone level until the tone becomes audible again. Repeat this procedure until the test tone remains audible although the level of the masking noise has been in- creased by more than 10 dB. This masking level - that is the level above which no further increase in the tone level was required for its audibility - is the correct masking level and this procedure should have produced the correct hear- ing threshold level for that test frequency. Note the correct masking level. The test tone may be presented either pulsed or continuous. Pulsed tones are preferably used for threshold determination. When both pulsed and con
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