Electroacoustics - Hearing aids - Part 9: Methods of measurement of the performance characteristics of bone conduction hearing aids (IEC 60118-9:2019)

This Standard specifies methods for the measurement of bone conduction hearing aid characteristics. The methods described will produce a suitable basis for the exchange of information or for direct comparison of the electroacoustical characteristics of bone conduction hearing aids. These methods are chosen to be practical and reproducible and are based on selected fixed parameters. The results obtained by the methods specified in this document express the performance under the conditions of measurement; however, the performance of the hearing aid under practical conditions of use will depend upon a number of factors (e.g. effective load impedance, environmental conditions, acoustical environment, etc.). This document defines methods of measurement of characteristics of bone conduction hearing aids both for - transcutaneously coupled devices measured on a mechanical coupler, meeting the requirements of IEC 60318-6, and - bone coupled/bone anchored devices measured on a skull simulator.

Elektroakustik - Hörgeräte - Teil 9: Verfahren zur Messung der Übertragungseigenschaften von Knochenleitungshörgeräten (IEC 60118-9:2019)

Électroacoustique - Appareils de correction auditive - Partie 9: Méthodes de mesure des caractéristiques fonctionnelles des appareils de correction auditive à conduction osseuse (IEC 60118-9:2019)

L'IEC 60118-9:2019 spécifie les méthodes permettant de mesurer les caractéristiques des appareils de correction auditive à conduction osseuse. Les résultats des méthodes décrites constitueront une base adaptée pour échanger des informations ou pour comparer directement les caractéristiques électroacoustiques des appareils de correction auditive à conduction osseuse. Ces méthodes sont choisies pour leur praticabilité et leur reproductibilité, et sont fondées sur des paramètres fixes sélectionnés. Les résultats obtenus par les méthodes spécifiées dans le présent document expriment le fonctionnement de l'appareil de correction auditive dans les conditions de mesure, mais le fonctionnement en conditions réelles d'utilisation dépend d'un ensemble de facteurs (impédance de charge effective, conditions d'environnement, environnement acoustique, etc.). Le présent document définit les méthodes permettant de mesurer les caractéristiques des appareils de correction auditive à conduction osseuse qui sont: • des appareils à couplage transcutané mesurés sur un coupleur mécanique satisfaisant aux exigences de l'IEC 60318-6; • des appareils à couplage/ancrage osseux mesurés sur un simulateur crânien. L'IEC 60118-9:2019annule et remplace la première édition parue en 1985. Cette édition constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente: a) ajout des appareils à couplage osseux mesurés sur un simulateur crânien; b) augmentation de la plage de fréquences de mesure à 8 000 Hz pour les appareils à couplage osseux.

Elektroakustika - Slušni pripomočki - 9. del: Metode za merjenje tehničnih lastnosti kostno prevodnih slušnih pripomočkov (IEC 60118-9:2019)

V tem standardu so opredeljene metode za merjenje lastnosti kostno prevodnih slušnih pripomočkov. Opisane metode bodo zagotovile ustrezno osnovo za izmenjavo informacij ali za neposredno primerjavo elektroakustičnih lastnosti kostno prevodnih slušnih pripomočkov. Izbrane metode so praktične in ponovljive ter temeljijo na izbranih nespremenljivih parametrih. Rezultati, pridobljeni z metodami, ki so navedene v tem dokumentu, prikazujejo delovanje v merilnih pogojih, vendar je učinkovitost slušnih pripomočkov pod praktičnimi pogoji uporabe odvisna od različnih dejavnikov (npr. učinkovita impedanca obremenitve, okoljski pogoji, akustično okolje itd.). Ta dokument določa metode za merjenje lastnosti kostno prevodnih slušnih pripomočkov tako za transkutano povezane naprave, ki se merijo na mehanskem spojniku in izpolnjujejo zahteve standarda IEC 60318-6, kot tudi za s kostjo spojene/na kost pritrjene naprave, merjene na lobanjskem simulatorju.

General Information

Status
Published
Publication Date
24-Nov-2019
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
20-Nov-2019
Due Date
25-Jan-2020
Completion Date
25-Nov-2019

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SLOVENSKI STANDARD
SIST EN IEC 60118-9:2020
01-januar-2020

Elektroakustika - Slušni pripomočki - 9. del: Metode za merjenje tehničnih lastnosti

kostno prevodnih slušnih pripomočkov (IEC 60118-9:2019)

Electroacoustics - Hearing aids - Part 9: Methods of measurement of the performance

characteristics of bone conduction hearing aids (IEC 60118-9:2019)
Elektroakustik - Hörgeräte - Teil 9: Verfahren zur Messung der
Übertragungseigenschaften von Knochenleitungshörgeräten (IEC 60118-9:2019)

Électroacoustique - Appareils de correction auditive - Partie 9: Méthodes de mesure des

caractéristiques fonctionnelles des appareils de correction auditive à conduction osseuse

(IEC 60118-9:2019)
Ta slovenski standard je istoveten z: EN IEC 60118-9:2019
ICS:
11.180.15 Pripomočki za gluhe osebe in Aids for deaf and hearing
osebe z okvaro sluha impaired people
17.140.50 Elektroakustika Electroacoustics
SIST EN IEC 60118-9:2020 en

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

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SIST EN IEC 60118-9:2020
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SIST EN IEC 60118-9:2020
EUROPEAN STANDARD EN IEC 60118-9
NORME EUROPÉENNE
EUROPÄISCHE NORM
November 2019
ICS 17.140.50
English Version
Electroacoustics - Hearing aids - Part 9: Methods of
measurement of the performance characteristics of bone
conduction hearing aids
(IEC 60118-9:2019)

Électroacoustique - Appareils de correction auditive - Partie Elektroakustik - Hörgeräte - Teil 9: Verfahren zur Messung

9: Méthodes de mesure des caractéristiques fonctionnelles der Übertragungseigenschaften von

des appareils de correction auditive à conduction osseuse Knochenleitungshörgeräten

(IEC 60118-9:2019) (IEC 60118-9:2019)

This European Standard was approved by CENELEC on 2019-10-21. CENELEC 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 CENELEC 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 CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the

same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,

Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the

Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and the United Kingdom.
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2019 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.

Ref. No. EN IEC 60118-9:2019 E
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SIST EN IEC 60118-9:2020
EN IEC 60118-9:2019 (E)
European foreword

The text of document 29/1025/FDIS, future edition 2 of IEC 60118-9, prepared by IEC/TC 29

"Electroacoustics" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as

EN IEC 60118-9:2019.
The following dates are fixed:

• latest date by which the document has to be implemented at national (dop) 2020-07-21

level by publication of an identical national standard or by endorsement

• latest date by which the national standards conflicting with the (dow) 2022-10-21

document have to be withdrawn

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

patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.

Endorsement notice

The text of the International Standard IEC 60118-9:2019 was approved by CENELEC as a European

Standard without any modification.

In the official version, for Bibliography, the following notes have to be added for the standards

indicated:
IEC 60068 (series) NOTE Harmonized as EN 60068 (series)
IEC 60263 NOTE Harmonized as EN IEC 60263
Under preparation. Stage at the time of publication: prEN IEC 60263.
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SIST EN IEC 60118-9:2020
EN IEC 60118-9:2019 (E)
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

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

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

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

applies.

NOTE 1 Where an International Publication has been modified by common modifications, indicated by (mod), the relevant

EN/HD applies.

NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available here:

www.cenelec.eu.
Publication Year Title EN/HD Year
IEC 60118-0 - Electroacoustics - Hearing aids - Part 0: EN 60118-0 -
Measurement of the performance characteristics
of hearing aids
IEC 60318-6 - Electroacoustics - Simulators of human head and EN 60318-6 -
ear - Part 6: Mechanical coupler for the
measurement on bone vibrators
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SIST EN IEC 60118-9:2020
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SIST EN IEC 60118-9:2020
IEC 60118-9
Edition 2.0 2019-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Electroacoustics – Hearing aids –
Part 9: Methods of measurement of the performance characteristics of bone
conduction hearing aids
Électroacoustique – Appareils de correction auditive –
Partie 9: Méthodes de mesure des caractéristiques fonctionnelles des appareils
de correction auditive à conduction osseuse
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 17.140.50 ISBN 978-2-8322-7332-6

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
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SIST EN IEC 60118-9:2020
– 2 – IEC 60118-9:2019 © IEC 2019
CONTENTS

FOREWORD ........................................................................................................................... 4

INTRODUCTION ..................................................................................................................... 6

1 Scope .............................................................................................................................. 7

2 Normative references ...................................................................................................... 7

3 Terms and definitions ...................................................................................................... 7

4 Measurement method .................................................................................................... 11

4.1 General ................................................................................................................. 11

4.2 Mechanical coupler ............................................................................................... 11

4.3 Skull simulator ...................................................................................................... 11

4.4 Measurement frequency range .............................................................................. 11

4.5 Reporting of data .................................................................................................. 12

5 Measurement enclosure and measurement equipment................................................... 12

5.1 General ................................................................................................................. 12

5.2 Unwanted stimuli in the test enclosure .................................................................. 12

5.3 Sound source ........................................................................................................ 12

5.4 Measurement system for the measurement of the vibratory force level

produced by a bone conduction hearing aid .......................................................... 12

5.5 Direct-current measuring system ........................................................................... 13

5.6 Magnetic field source for ETLS and MMSL measurements .................................... 13

6 Measurement conditions ................................................................................................ 14

6.1 General ................................................................................................................. 14

6.2 Applying the bone vibrator to the mechanical coupler or skull simulator ............. 14

6.2.1 Transcutaneously coupled devices ................................................................ 14

6.2.2 Bone coupled devices ................................................................................. 14

6.3 Control of the sound field ...................................................................................... 15

6.3.6 Battery or supply voltage ............................................................................... 17

6.3.7 Settings of controls ........................................................................................ 18

6.4 Ambient conditions................................................................................................ 18

6.4.1 Measurement space ...................................................................................... 18

6.4.2 Bone vibrator, mechanical coupler and skull simulator ................................. 18

7 Measurement procedures .............................................................................................. 19

7.1 Frequency response curves .................................................................................. 19

7.2 OVFL90 frequency response curve ....................................................................... 19

7.3 Full-on acousto-mechanical sensitivity level frequency response ....................... 20

7.4 Basic vibratory force level frequency response ..................................................... 21

7.4.1 Measurement procedure ................................................................................ 21

7.4.2 Frequency range ........................................................................................... 21

7.5 Total harmonic distortion ....................................................................................... 21

7.6 Equivalent input noise ........................................................................................... 22

7.7 Battery current ...................................................................................................... 22

7.8 Measurements for hearing aids having an induction pick-up coil ........................... 22

7.8.1 General ......................................................................................................... 22

7.8.2 Equivalent test loop sensitivity (ETLS) ........................................................... 23

7.8.3 Maximum HFA magneto-mechanical sensitivity level (HFA- MMSL) of

induction pick-up coil ..................................................................................... 23

8 Maximum permitted expanded uncertainty of measurements ......................................... 23

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SIST EN IEC 60118-9:2020
IEC 60118-9:2019 © IEC 2019 – 3 –

Bibliography .......................................................................................................................... 26

Figure 1 – Example of a bone coupled device (hearing aid with integral bone vibrator)

mounted on a skull simulator ................................................................................................ 15

Figure 2 – Example of a transcutaneously coupled device (spectacle hearing aid with

an integral bone vibrator mounted in the spectacle arm) under measurement ....................... 16

Figure 3 – Example of a transcutaneously coupled device (hearing aid with external

bone vibrator) mounted on the mechanical coupler ............................................................... 17

Figure 4 – Example of OVFL90 curve and basic force level frequency response curve .......... 20

Figure 5 – Relationship between tolerance limits, corresponding acceptance intervals

and the maximum permitted uncertainty of measurement, U .......................................... 24

MAX

Table 1 – Resistors and open circuit voltages for zinc-air battery simulators ......................... 18

Table 2 – Distortion test frequencies and input sound pressure levels ................................... 22

Table 3 – Example uncertainty budget .................................................................................. 25

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SIST EN IEC 60118-9:2020
– 4 – IEC 60118-9:2019 © IEC 2019
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTROACOUSTICS –
HEARING AIDS –
Part 9: Methods of measurement of the performance
characteristics of bone conduction hearing aids
FOREWORD

1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

all national electrotechnical committees (IEC National Committees). The object of IEC is to promote

international co-operation on all questions concerning standardization in the electrical and electronic fields. To

this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,

Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as "IEC

Publication(s)"). Their preparation is entrusted to technical committees; any IEC National Committee interested

in the subject dealt with may participate in this preparatory work. International, governmental and non-

governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely

with the International Organization for Standardization (ISO) in accordance with conditions determined by

agreement between the two organizations.

2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international

consensus of opinion on the relevant subjects since each technical committee has representation from all

interested IEC National Committees.

3) IEC Publications have the form of recommendations for international use and are accepted by IEC National

Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC

Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any

misinterpretation by any end user.

4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications

transparently to the maximum extent possible in their national and regional publications. Any divergence

between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in

the latter.

5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity

assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any

services carried out by independent certification bodies.

6) All users should ensure that they have the latest edition of this publication.

7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and

members of its technical committees and IEC National Committees for any personal injury, property damage or

other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and

expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC

Publications.

8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is

indispensable for the correct application of this publication.

9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of

patent rights. IEC shall not be held responsible for identifying any or all such patent rights.

International Standard IEC 60118-9 has been prepared by IEC technical committee 29:

Electroacoustics.

This second edition cancels and replaces the first edition published in 1985. This edition

constitutes a technical revision.

This edition includes the following significant technical changes with respect to the previous

edition:
a) includes bone coupled devices measured on a skull simulator;
b) measurement frequency range increased to 8 000 Hz for bone coupled devices.
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SIST EN IEC 60118-9:2020
IEC 60118-9:2019 © IEC 2019 – 5 –
The text of this International Standard is based on the following documents:
FDIS Report on voting
29/1025/FDIS 29/1029/RVD

Full information on the voting for the approval of this International Standard can be found in

the report on voting indicated in the above table.

This document has been drafted in accordance with the ISO/IEC Directives, Part 2.

A list of all parts in the IEC 60118 series, published under the general title Electroacoustics –

Hearing aids, can be found on the IEC website.

The committee has decided that the contents of this document will remain unchanged until the

stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to

the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates

that it contains colours which are considered to be useful for the correct

understanding of its contents. Users should therefore print this document using a

colour printer.
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SIST EN IEC 60118-9:2020
– 6 – IEC 60118-9:2019 © IEC 2019
INTRODUCTION

IEC 60118-0 gives information on methods of measurement for air conduction hearing aids.

The majority of hearing aids in use are of this type, but a small percentage use a bone

vibrator instead of an earphone. The use of a bone vibrator requires a different method of

measuring the output from the hearing aid and also makes it impractical to measure

amplification directly in terms of acoustic gain.

Amplification in the case of an air conduction hearing aid is expressed as the difference

between the output sound pressure level in an acoustic coupler or ear simulator and the

input sound pressure level measured in a specified manner. However, with bone

conduction hearing aids, the input is in terms of sound pressure level, but the output will be

in terms of mechanical vibration measured as a vibratory force or force level.

By means of information provided in this document, the performance of hearing aids with

bone vibrator outputs which do not form an integral part of the hearing aid, for example body-

worn, behind-the-ear hearing aids, or bone conduction implant systems with an external bone

vibrator, can be measured in a similar manner to aids with air conduction outputs as

described in IEC 60118-0.

Where the bone vibrator forms an integral part of the hearing aid, or where it is attached in

some fixed manner to the hearing aid, for example a bone coupled (bone anchored) hearing

aid, its performance cannot be measured in the same way as for body-worn aids, due to the

large dimensions of the mechanical coupler. This document recommends a pressure method

of controlling the input sound pressure level to the hearing aid microphone. As an alternative

to the pressure method, storage of a test enclosure frequency response correction curve can

be used. This method is referred to as the "substitution method".
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SIST EN IEC 60118-9:2020
IEC 60118-9:2019 © IEC 2019 – 7 –
ELECTROACOUSTICS –
HEARING AIDS –
Part 9: Methods of measurement of the performance
characteristics of bone conduction hearing aids
1 Scope

This part of IEC 60118 specifies methods for the measurement of bone conduction hearing

aid characteristics.

The methods described will produce a suitable basis for the exchange of information or for

direct comparison of the electroacoustical characteristics of bone conduction hearing aids.

These methods are chosen to be practical and reproducible and are based on selected fixed

parameters.

The results obtained by the methods specified in this document express the performance

under the conditions of measurement; however, the performance of the hearing aid under

practical conditions of use will depend upon a number of factors (e.g. effective load

impedance, environmental conditions, acoustical environment, etc.).

This document defines methods of measurement of characteristics of bone conduction

hearing aids both for
• transcutaneously coupled devices measured on a mechanical coupler, meeting the
requirements of IEC 60318-6, and
• bone coupled/bone anchored devices measured on a skull simulator.

NOTE 1 A skull simulator is a mechanical coupler designed to present a specific mechanical impedance to

mechanically coupled vibrator.

NOTE 2 Throughout this document, all sound pressure levels specified are referred to 20 µPa. When

appropriate, sound pressure level will be abbreviated to SPL.
2 Normative references

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

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

cited applies. For undated references, the latest edition of the referenced document (including

any amendments) applies.

IEC 60118-0, Electroacoustics – Hearing aids – Part 0: Measurement of the performance

characteristics of hearing aids

IEC 60318-6, Electroacoustics – Simulators of human head and ear – Part 6: Mechanical

coupler for the measurement on bone vibrators
ISO 3, Preferred numbers – Series of preferred numbers
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
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SIST EN IEC 60118-9:2020
– 8 – IEC 60118-9:2019 © IEC 2019

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

addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
bone conduction hearing aid
wearable instrument intended to aid a person with impaired hearing using an

electromechanical transducer intended to produce the sensation of hearing by vibrating the

cranial bones

Note 1 to entry: A bone conduction hearing aid usually consists of a microphone, amplifier, signal processor, and

bone vibrator, powered by a low-voltage battery, and possibly also containing an induction pick-up coil. It is fitted

using audiometric and prescriptive methods.

Note 2 to entry: The bone vibrator of a hearing aid can be integrated in the same housing with the hearing aid,

can be driven via a cable solution and placed in a separate housing, or can be driven via an inductive link and

implanted in the skull.

Note 3 to entry: Bone conduction hearing aids can be placed on the body (body worn), behind-the-ear (BTE), or

in the mastoid area (ear level).
3.2
transcutaneously coupled hearing aid

bone conduction hearing aid using a device that is coupled by an attractive or a static force to

a human head
3.3
bone coupled hearing aid

device that is implanted or rigidly coupled to the skull bone, via a mechanical coupling or an

abutment to the human head

Note 1 to entry: A bone coupled bone conduction hearing aid is often named a bone-anchored device.

3.4
vibratory force level
VFL

twenty times the logarithm to the base 10 of the ratio of the RMS value of the force

transmitting the vibration to the reference value of 1 µN, expressed in decibels
Note 1 to entry: This note applies to the French language only.
3.5
mechanical coupler

device for measuring the vibratory force level output of a transcutaneously coupled hearing

aid, where the force level is measured by a calibrated mechano-electric transducer coupled to

the source
EXAMPLE As described in IEC 60318-6.
3.6
skull simulator

device for measuring the vibratory force level output of a bone coupled hearing aid, where the

force level is measured by a calibrated mechano-electric transducer coupled to the source

3.7
acousto-mechanical sensitivity

quotient of the vibratory force, produced on a mechanical coupler or a skull simulator by the

bone conduction hearing aid and the sound pressure at the reference point of the hearing aid

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SIST EN IEC 60118-9:2020
IEC 60118-9:2019 © IEC 2019 – 9 –
3.8
acousto-mechanical sensitivity level
AMSL

twenty times the logarithm to the base 10 of the ratio of the acousto-mechanical sensitivity to

the reference sensitivity of 1 µN/20 µPa, expressed in decibels

Note 1 to entry: To calculate the acousto-mechanical sensitivity level from measurements made in this document,

the following formula can be used:
AMSL = VFL – Input SPL
where
VFL re 1 µN is expressed in decibels.
Note 2 to entry: This note applies to the French language only.
3.9
input sound pressure level
sound pressure level at the hearing aid reference point
3.10
basic vibratory force level frequency response curve

force level frequency response curve obtained with the gain control in the reference test

setting and with an input SPL of 60 dB
3.11
input-output characteristic

plot of the output force level, for a single frequency, measured on a mechanical coupler or a

skull simulator on the ordinate, against the sound pressure level applied to the hearing aid on

the abscissa, with equal decibel scale divisions on each axis
3.12
vertical reference

line through or on a hearing aid which is vertical when the aid is positioned as worn on a head

and a torso simulator
3.13
reference point

point on the bone conduction hearing aid chosen for the purpose of defining its position

3.14
high-frequency average
HFA
average of AMSL or VFL in decibels at 1 000 Hz, 1 600 Hz and 2 500 Hz
Note 1 to entry: This note applies to the French language only.
3.15
gain control
manually or electronically operated control for the adjustment of overall output
3.16
OVFL90
output vibratory force level for 90 dB input SPL

VFL developed on a mechanical coupler or a skull simulator with an input SPL of 90 dB with

the gain control of the hearing aid full-on

Note 1 to entry: It is recognized that the maximum output level may occur with more, or occasionally with less,

input SPL than 90 dB. However, the differences are usually small over the frequency range of interest and the

input SPL of 90 dB makes automatic recording of the OVFL90 curve very convenient.

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SIST EN IEC 60118-9:2020
– 10 – IEC 60118-9:2019 © IEC 2019
3.17
high-frequency average of the OVFL90

high-frequency average of the output vibratory force level for an input sound pressure level of

90 dB
3.18
full-on HFA-AMSL
full-on high-frequency average acousto-mechanical sensitivity level

HFA for an input SPL of 50 dB when the gain control of a bone conduction hearing aid is at its

full-on position

Note 1 to entry: The hearing aid shall be set to maximum possible gain setting. Where possible, the AGC function

of AGC hearing aids shall be set to have minimum effect for all measurements.

Note 2 to entry: The manufacturer shall specify the full-on settings used for measurements by providing either a

test program, a set of programmed settings or by reference to physical control settings.

Note 3 to entry: Other adaptive features, such as some directionality, noise suppression, and feedback

suppression systems etc., which may affect the validity of measurements made with steady-state pure-tone signals,

should be disabled. The settings used for measurements shall be specified by the manufacturer by providing either

a test program, a set of programmed settings or by reference to physical control settings.

3.19
RTS
reference test setting of the gain control

setting of the gain control required to produce, for an input SPL of 60 dB, an HFA-AMSL

within ±1,5 dB of the HFA-OVFL90 minus 77 dB, or, if the full-on HFA gain for an input

...

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