BS-6083-8-1985 IEC-60118-8-1983.pdf

BRITISH STANDARD BS 6083-8: 1985 IEC 118-8: 1983 Hearing aids Part 8: Methods for measurement of the performance characteristics of hearing aids under simulated in situ working conditions UDC 616.28-76:620.162 Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 04:48:28 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6083-8:1985 This British Standard, having been prepared under the direction of the Electronic Equipment Standards Committee, was published under the authority of the Board of BSI and comes into effect on 28 February 1985 © BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference EEL/24 Draft for comment 84/28670 DC ISBN 0 580 14407 0 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Electronic Equipment Standards Committee (EEL/-) to Technical Committee EEL/24 upon which the following bodies were represented: British Radio and Electronic Equipment Manufacturers Association British Telecommunications Department of Health and Social Security Department of Trade and Industry (National Physical Laboratory) Institution of Electronic and Radio Engineers Royal National Institute for the Deaf Society of Hearing Aid Audiologists Limited The following bodies were also represented in the drafting of the standard, through subcommittees and panels: British Medical Association British Society of Audiology Health and Safety Executive Institute of Actuaries Hearing Aid Industry Association Institute of Sound and Vibration Research Manchester Area Health Authority Medical Research Council Ministry of Defence National Coal Board Royal Aeronautical Society Amendments issued since publication Amd. No.Date of issueComments Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 04:48:28 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6083-8:1985 © BSI 10-1999i Contents Page Committees responsibleInside front cover National forewordii 1Scope1 2Object1 3Limitations1 4Explanation of terms1 5Test equipment3 6Test conditions4 7Measurements5 8Frequency response recording charts7 Appendix A General requirements for a manikin10 Figure 1 Manikin geometrical references8 Figure 2 Co-ordinator for angles of azimuth and elevation9 Publications referred toInside back cover Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 04:48:28 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6083-8:1985 ii © BSI 10-1999 National foreword This Part of BS 6083 has been prepared under the direction of the Electronic Equipment Standards Committee and is identical with IEC Publication 118-8 “Hearing aids Part 8: Measurement of the performance characteristics of hearing aids under simulated in situ working conditions” published in 1983 by the International Electrotechnical Commission (IEC). BS 6083 consists of the following Parts: Part 0:1984: Methods for measurement of electroacoustical characteristics; Part 1:1984: Method for measurement of characteristics of hearing aids with induction pick-up coil input; Part 2:1984: Methods for measurement of electroacoustical characteristics of hearing aids with automatic gain control circuits; Part 3:1984: Methods for measurement of electroacoustical characteristics of hearing aid equipment not entirely worn on the listener; Part 4:1981: Specification for magnetic field strength in audio-frequency induction loops for hearing aid purposes; Part 5:1984: Specification for dimensions of the nipple and sealing device for insert earphones; Part 6: External electrical inputs to personal hearing aids1); Part 7:1985: Methods for measurement of the performance characteristics of hearing aids for quality inspection on delivery; Part 8:1985: Methods for measurement of the performance characteristics of hearing aids under simulated in situ working conditions; Part 9: Method for measurement of characteristics of hearing aids with bone vibrator outputs1); Part 10: Guide to hearing aid standards1); Part 11:1984: Specification for symbols and other markings on hearing aids and related equipment. Terminology and conventions. The text of the International Standard has been approved as suitable for publication as a British Standard without deviation. Some terminology and certain conventions are not identical with those used in British Standards. There is at present no corresponding British Standard for IEC Publication XXX, referred to in Appendix A. The IEC standard is in preparation and on publication, consideration will be given to its implementation as an identical British Standard. 1) In preparation. Cross-references International StandardsCorresponding British Standards BS 6083: Hearing aids IEC 118-0:1980Part 0:1984: Methods for measurement of electroacoustical characteristics (Identical) IEC 118-7:1983Part 7:1985: Methods for measurement of the performance characteristics of hearing aids for quality inspection on delivery (Identical) IEC 263:1982BS 6397:1983 Specification for scales and sizes for plotting frequency characteristics and polar diagrams (Identical) Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 04:48:28 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6083-8:1985 © BSI 10-1999iii A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i to iv, pages 1 to 10, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 04:48:28 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iv blank Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 04:48:28 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6083-8:1985 © BSI 10-19991 1 Scope This report applies to the performance characteristics of hearing aids. Measuring methods that take into account the acoustical influence of the wearer on the performance of hearing aids are important, particularly when the results are to be used to assist in the fitting of hearing aids. The information obtained using this report is likely to be more relevant to the fitting of hearing aids than that provided by publications concerned with type approval and quality control such as IEC Publication 118-0: Hearing Aids: Part 0: Measurement of Electroacoustical Characteristics, and IEC Publication 118-7: Hearing Aids, Part 7: Measurement of Performance Characteristics of Hearing Aids for Quality Inspection for Delivery Purposes. The methods specified in this report require a device such as a manikin to simulate the presence of the wearer. Work on a report for a head and torso simulator is in progress. Pending an agreement on a manikin, it has been found necessary to establish certain guidelines for simulated in situ measurements of hearing aids. The recommended methods are described in this report. 2 Object The purpose of this report is to describe test methods which simulate the acoustical effects of a median adult wearer on the performance of a hearing aid. 3 Limitations 3.1 The results obtained under simulated in situ conditions may differ substantially from results obtained on an individual person, due to anatomical variations of heads, torsos, pinnas, ear canals, and eardrums. Care should therefore be taken when interpreting the results. 3.2 The methods recommended in this report give information on the measurement of the following parameters that are considered important for the evaluation of the performance of a hearing aid as normally worn, and for which simulated in situ conditions are considered essential: full-on insertion gain; insertion frequency response; directional characteristics; simulated in situ OSPL90. NOTEThe accuracy and repeatability of results obtained under simulated in situ conditions cannot generally be expected to be as good as when using the free-field technique laid down in IEC Publication 118-0. The use of simulated in situ conditions for the measurements of hearing aid parameters other than those listed above is therefore not included. 4 Explanation of terms 4.1 Sound pressure level Throughout this report all sound pressure levels (abbreviated SPL) are referred to 20 4Pa. 4.2 Pinna simulator A device which has the approximate shape and dimensions of a median adult human pinna. 4.3 Ear simulator An ear simulator is a device for measuring the output sound pressure of an earphone under well defined loading conditions in a specified frequency range. It consists essentially of a principal cavity, acoustic load networks and a calibrated microphone. The location of the microphone is chosen so that the sound pressure at the microphone corresponds approximately to the sound pressure existing at the human eardrum. 4.4 Occluded-ear simulator An ear simulator which simulates the inner part of the ear canal, from the tip of an ear insert to the eardrum. 4.5 Ear canal extension A device which connects the concha portion of the pinna simulator with the outer (reference plane) face of the occluded ear simulator, simulating the outer part of the ear canal excluding the pinna. 4.6 Ear insert simulator A device used to represent the acoustic coupling between an earphone and the ear canal (e.g. an earmould or a similar device without a connecting tube). 4.7 Manikin (head and torso simulator) A head and torso simulator extending downward from the top of the head to the waist and designed to simulate the acoustic diffraction produced by a median adult human head and torso. The head includes two pinna simulators, and contains at least one occluded ear simulator. 4.8 Reference point of a subject or manikin The point bisecting the line joining the centres of the openings of the ear canals (at the junction between concha and ear canal) (see Figure 1, page 8). 4.9 Plane of symmetry of the manikin A plane passing through the reference point of the manikin that divides the left and right portions of the manikin into symmetrical halves (see Figure 1). Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 04:48:28 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6083-8:1985 2 © BSI 10-1999 4.10 Axis of rotation of the manikin A straight line passing through the reference point of the manikin and lying in the plane of symmetry of the manikin, and having a direction that would be vertical if the manikin were mounted in a position corresponding to that of a standing person (and about which the manikin can be rotated) (see Figure 1). 4.11 Reference plane of the manikin A plane perpendicular to the axis of rotation containing the reference point of the manikin (see Figure 1). 4.12 Test point A reproducible position in the test space at which the sound pressure level is measured with the manikin absent and at which the reference point of the manikin is to be located for test purposes. 4.13 Reference input sound pressure level The free field sound pressure level at the test point in the absence of the manikin. 4.14 Test axis The line joining the test point and the centre of the sound source (see Figure 2, page 9). 4.15 Test plane (for measurement of the uniformity of the free field wavefront) A plane perpendicular to the test axis and containing the test point. 4.16 Azimuth angle of sound incidence (F F) The angle between the plane of symmetry of the manikin (see Figure 2) and the plane defined by the axis of rotation and the test axis. When the manikin faces the sound source the azimuth angle of sound incidence is defined as 0°. When the right ear of the manikin faces the sound source, the azimuth angle is defined as 90°. When the left ear faces the sound source, the angle is defined as 270°. 4.17 Elevation angle of sound incidence (! !) The angle between the reference plane of the manikin and the test axis (see Figure 2). When the top of the manikin points towards the sound source the elevation angle is defined as + 90°. When the test axis lies in the reference plane, the elevation angle is defined as 0°. 4.18 Reference position of the manikin in the test space The position of the manikin in the test space that meets the following conditions: the reference point coincides with the test point; the angles of azimuth and elevation are both equal to zero. 4.19 Manikin unoccluded ear gain The difference between the sound pressure level in the unoccluded ear simulator and the reference input sound pressure level. This will be a function of manikin position. 4.20 Manikin unoccluded ear gain frequency response (MFR) Manikin unoccluded ear gain expressed as a function of frequency. MFR is a function of manikin position. 4.21 Simulated in situ gain (SISG) The difference between the SPL in the ear simulator produced by the hearing aid and the reference input SPL. This will be a function of manikin position. 4.22 Simulated in situ gain frequency response (SISGFR) SISG expressed as a function of frequency. 4.23 Simulated insertion gain (SIG) The difference between the SPL in the ear simulator produced by the hearing aid and the SPL in the ear simulator with the hearing aid absent (is equal to SISG-MFR). This will be a function of manikin position. 4.24 Full-on simulated insertion gain The SIG obtainable from a hearing aid with the gain control at maximum (full-on) and at stated settings of the other hearing aid controls. 4.25 Simulated insertion gain frequency response (SIGFR) SIG expressed as a function of frequency. 4.26 Manikin unoccluded-ear directional response (MDR) The sound pressure level in the ear simulator at a stated frequency as a function of azimuth and/or elevation angle with the hearing aid absent. 4.27 Simulated in situ directional response (SISDR) The sound pressure level in the ear simulator produced by the hearing aid as a function of azimuth and/or elevation angle at a stated frequency, gain value and input level. 4.28 Simulated insertion directional response (SIDR) The difference between SISDR and MDR. Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 04:48:28 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6083-8:1985 © BSI 10-19993 4.29 Simulated in situ OSPL90 (output sound pressure level for 90 dB input SPL) The output sound pressure level in the ear simulator produced by the hearing aid at a specified frequency with the hearing aid gain control at maximum (full-on) and a reference input SPL of 90 dB. 4.30 Simulated in situ OSPL90 frequency response Simulated in situ OSPL90 expressed as a function of frequency. 5 Test equipment 5.1 Acoustical requirements for the test space 5.1.1 The test space shall provide essentially free-field conditions over the frequency range 200 Hz to 8 000 Hz. Essentially free-field conditions are considered established when the sound p