EN 60118-2:1995/A2:1997
(Amendment)Hearing aids - Part 2: Hearing aids with automatic gain control circuits
Hearing aids - Part 2: Hearing aids with automatic gain control circuits
Adds a new clause 10 to IEC 60118-2 second edition : Frequency response of hearing heads with AGC circuits in operation using steady-state broad-band signals.
Hörgeräte - Teil 2: Hörgeräte mit automatischer Verstärkungsregelung
Appareils de correction auditive - Partie 2: Appareils de correction auditive comportant des commandes automatiques de gain
Ajoute un nouvel article 10 à la CEI 60118-2 deuxième édition : Courbe de réponse en fréquence des appareils de correction auditive comportant des commandes automatiques de gain en fonctionnement à l'aide de signaux d'entrée à large bande en régime permanent.
Slušni pripomočki – 2. del: Slušni pripomočki z vezji za samodejno krmiljenje ojačenja – Dopolnilo A2 (IEC 60118- 2:1983/A2:1997)
General Information
Relations
Standards Content (Sample)
SLOVENSKI SIST EN 60118-2:2004/A2:2006
STANDARD
februar 2006
Slušni pripomočki – 2. del: Slušni pripomočki z vezji za samodejno krmiljenje
ojačenja – Dopolnilo A2 (IEC 60118- 2:1983/A2:1997)
Hearing aids - Part 2: Hearing aids with automatic gain control circuits; Amendment
A2 (IEC 60118- 2:1983/A2:1997)
ICS 11.180.15 Referenčna številka
SIST EN 60118-2:2004/A2:2006(en)
© Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno
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NORME CEI
INTERNATIONALE
IEC
60118-2
INTERNATIONAL
1983
STANDARD
AMENDEMENT 2
AMENDMENT 2
1997-05
Amendement 2
Appareils de correction auditive –
Partie 2:
Appareils de correction auditive comportant
des commandes automatiques de gain
Amendment 2
Hearing aids –
Part 2:
Hearing aids with automatic gain
control circuits
IEC 1997 Droits de reproduction réservés Copyright - all rights reserved
International Electrotechnical Commission 3, rue de Varembé Geneva, Switzerland
Telefax: +41 22 919 0300 e-mail: inmail@iec.ch IEC web site http: //www.iec.ch
CODE PRIX
Commission Electrotechnique Internationale
K
PRICE CODE
International Electrotechnical Commission
Pour prix, voir catalogue en vigueur
For price, see current catalogue
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60118-2 Amend. 2 © IEC:1997 – 3 –
FOREWORD
This amendment has been prepared by the IEC technical committee 29: Electroacoustics.
The text of this amendment is based on the following documents:
FDIS Report on voting
29/350/FDIS 29/358/RVD
Full information on the voting for the approval of this amendment can be found in the report
on voting indicated in the above table.
____________
Page 3
CONTENTS
Add the title of the new clause 10 and the new annexes B and C as follows:
10 Frequency response of hearing aids with AGC circuits in operation
using steady-state broad-band signals
Annexes
B Smoothed data presentation
C Bibliography
Page 5
Add the following list of standards:
IEC 60118-0: 1983, Hearing aids – Part 0: Measurement of electroacoustical characteristics
Amendment 1: 1994
IEC 60711: 1981, Occluded-ear simulator for the measurement of earphones coupled to the
ear by ear inserts
IEC 61260: 1995, Electroacoustics – Octave-band and fractional-octave-band filters
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60118-2 Amend. 2 © IEC:1997 – 5 –
Page 9
3 Conditions
Delete 3.2
Renumber 3.3 to become 3.2
4 Explanation of terms
Add the following new definitions after 4.9 (page 3 in amendment 1):
4.10 Overall root-mean-square sound pressure level (overall r.m.s. SPL)
The root-mean-square sound pressure level with measurement bandwidth equal to the
frequency range covered by the one-third-octave frequency bands (see IEC 61260) from
200 Hz to 8 000 Hz.
4.11 One-third-octave band level
The level of that part of the signal contained within a band one-third-octave wide as defined
in IEC 61260.
4.12 Auto-spectrum (power spectrum)
The power spectrum of either the input signal (G ) to or the output signal (G ) from a
AA BB
hearing aid in the frequency domain. It is computed by multiplying the Fourier transform of
the signal by the complex conjugate of the Fourier transform of the same signal.
4.13 Cross-spectrum (G )
AB
The degree to which the same signal frequencies are mutually present in the input and
output of a hearing aid. It is computed by multiplying the complex conjugate of the Fourier
transform of the input signal to the hearing aid by the Fourier transform of the output signal
from the hearing aid.
4.14 Coherence
A number ranging from 0 to 1 showing to what degree the output from a hearing aid is
correlated to the input. Coherence for a random noise test signal is reduced by non-linearity
and by system noise. The coherence is calculated from the auto- and cross-spectrum
averages as follows:
2
G
AB
Coherence =
GG•
AA BB
4.15 Synchronous analysis
Analysis which is synchronized with the period of the input signal, for example with the
periodicity of pseudo-random noise.
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60118-2 Amend. 2 © IEC:1997 – 7 –
Page 15
Add, after clause 9, the following clause 10 (page 9 in amendment 1):
10 Frequency response of hearing aids with AGC circuits in operation
using steady-state broad-band input signals
10.1 General
The frequency response of electroacoustic systems, including hearing aids, has traditionally
been obtained using a swept pure tone input signal whose level is held constant while the
output of the system is measured over the frequency range of interest. However, other
methods have evolved for obtaining frequency responses of electronic systems as a result
of the recent proliferation of digital spectrum analysers that utilise steady-state broad-band
noise as one of their test signals. A time-stationary, steady-state broad-band noise, which is
more typica
...
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