SIST ETS 300 488 E1:2003

SLOVENSKI STANDARD
01-december-2003
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Terminal Equipment (TE); Telephony for hearing impaired people; Characteristics of
telephone sets that provide additional receiving amplification for the benefit of the
hearing impaired
Ta slovenski standard je istoveten z: ETS 300 488 Edition 1
ICS:
11.180.15 3ULSRPRþNL]DJOXKHRVHEHLQ Aids for deaf and hearing
RVHEH]RNYDURVOXKD impaired people
33.050.10 Telefonska oprema Telephone equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN ETS 300 488
TELECOMMUNICATION January 1996
STANDARD
Source: ETSI TC-TE Reference: DE/TE-04092
ICS: 33.020
Telephony, amplification, ISDN, PSTN, TE, PWSN
Key words:
Terminal Equipment (TE);
Telephony for hearing impaired people;
Characteristics of telephone sets that provide additional
receiving amplification for the benefit of the hearing impaired
ETSI
European Telecommunications Standards Institute
ETSI Secretariat
F-06921 Sophia Antipolis CEDEX - FRANCE
Postal address:
650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE
Office address:
c=fr, a=atlas, p=etsi, s=secretariat - secretariat@etsi.fr
X.400: Internet:
Tel.: +33 92 94 42 00 - Fax: +33 93 65 47 16
*
Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and the
foregoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 1996. All rights reserved.

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ETS 300 488: January 1996
Whilst every care has been taken in the preparation and publication of this document, errors in content,
typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to
"ETSI Editing and Committee Support Dept." at the address shown on the title page.

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ETS 300 488: January 1996
Contents
Foreword .5
Introduction.5
1 Scope .7
2 Normative references.7
3 Definitions and abbreviations .7
3.1 Definitions .7
3.2 Abbreviations .7
4 Sending characteristics .8
4.1 General .8
4.2 Sensitivity frequency response .8
4.3 Sending Loudness Rating.8
5 Receiving characteristics.8
5.1 General .8
5.2 Sensitivity frequency response .8
5.3 Receiving Loudness Rating .8
5.4 Restoring normal receive amplification.9
6 Other characteristics .9
6.1 Sidetone.9
6.2 Stability.9
6.2.1 Analogue and digital sets .9
6.2.2 Additional stability test .10
6.3 Echo path loss .10
6.3.1 Echo Return Loss (ERL) .10
6.3.2 Weighted Terminal Coupling Loss (TCLw) .10
6.4 Distortion.10
6.4.1 Sending .10
6.4.2 Receiving.10
6.4.3 Sidetone .10
6.4.4 Sending power handing capability.10
6.4.5 Receiving power handling capability .11
6.5 Noise.11
6.5.1 Sending .11
6.5.2 Receiving.11
6.6 Acoustic shock.11
7 Testing methods.11
7.1 Analogue telephones .11
7.2 Digital telephones .12
7.3 Summary of test methods.13
Annex A (normative): Packaging, labelling and user instructions .14
A.1 Packaging and labelling .14
A.2 User instructions.14
A.3 Product suppliers information.14
Annex B (informative): Bibliography.15

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ETS 300 488: January 1996
History. 16

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ETS 300 488: January 1996
Foreword
This European Telecommunication Standard (ETS) was produced by the Terminal Equipment (TE)
Technical Committee of the European Telecommunications Standards Institute (ETSI).
Transposition dates
Date of adoption of this ETS: 12 January 1996
Date of latest announcement of this ETS (doa): 30 April 1996
Date of latest publication of new National Standard
or endorsement of this ETS (dop/e): 31 October 1996
Date of withdrawal of any conflicting National Standard (dow): 31 October 1996
Introduction
This ETS specifies the requirements for telephones with receive amplification intended to aid the hearing
impaired. A significant proportion of the population is disabled by varying degrees of hearing loss, often
associated with a reduction of speech discrimination ability. Amplification can only replace the lost
sensitivity.
The group most likely to receive the greatest benefit from the use of a telephone with additional receive
amplification are those with moderate to severe hearing losses in the range of 35 dB to 80 dB.
In setting the numerical values in this ETS, consideration has been given to the fact that the sound
pressure levels at the ear during a telephone conversation can be up to 30 dB above those occurring in
normal face-to-face conversation (at 1 metre distance). As hearing impaired people do not necessarily
have elevated thresholds of loudness discomfort, some form of output limitation will be required. Recent
work has indicated that Automatic Gain Control (AGC) may provide a better means of limitation than peak
clipping. In addition, it is recognized that in order to give maximum intelligibility to some hearing impaired
people, the frequency response may require shaping.
Two types of application are envisaged. Firstly, where the telephone is to be used in the main by a hearing
impaired person, secondly where it will be used by persons with a range of hearing acuity. In the first case
it will be advantageous to maintain the receive amplification (the level of which is selected by means of a
volume control set by the hearing impaired user) when the handset is replaced. In the second, it may be
preferable to arrange that the additional amplification is brought into use by the operation of a latching
switch that automatically resets the gain to nominal level when the handset is replaced in its rest position.
The use of voice switched attenuation, perhaps 10 dB to 12 dB, may be necessary to provide protection
against instability, in particular for the first case, and could also improve the discrimination against the
ambient noise received through the sidetone path.
It is estimated that with the provision of additional amplification to the levels recommended below, possibly
up to 80 % of hearing impaired users would benefit even when not using their hearing aids to couple to the
telephone set. If a hearing aid is worn in addition and inductive coupling is also provided, then the
proportion of hearing impaired users who will be able to have satisfactory telephone conversations will
increase further. It is, however, pointed out that with a high gain setting selected, the sound level and/or
inductive field at the earphone may be considerably higher than normally experienced by hearing aid
microphones and/or inductive pick-up coils and, on short telephone connections in particular, there is a
very real possibility of overloading the input stages of the hearing aid. For this reason, this ETS permits
the Receiving Loudness Rating (RLR) to be adjusted to be quieter than the requirements of the relevant
terminal standard.
The inclusion of additional receiving amplification does not reduce or replace existing technical standards
that apply to a handset. Additional receiving amplification may be combined with other additional
functionality, such as inductive coupling or additional earpieces, provided specifically for people with
special needs.
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ETS 300 488: January 1996
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ETS 300 488: January 1996
1 Scope
This ETS specifies the electro-acoustic performance characteristics of telephony terminals which are
intended for direct application to the ear (e.g. traditional handsets, operators' headsets) and which
provide, at the earphone, additional amplification in the receiving direction compared with the Receiving
Loudness Rating (RLR) specified in the relevant terminal standard.
This ETS applies to telephony terminals that can be connected to the Public Switched Telephone
Network (PSTN) or the coincident S and T reference point of the basic access of the Integrated
Services Digital Network (ISDN).
Hands free or loudspeaking devices and extra amplification in sending for the benefit of people having
speech impairments are outside the scope of this ETS.
2 Normative references
This ETS incorporates by dated and undated reference, provisions from other publications. These
normative references are cited at the appropriate places in the text and the publications are listed
hereafter. For dated references, subsequent amendments to or revisions of any of these publications
apply to this ETS only when incorporated in it by amendment or revision. For undated references the latest
edition of the publication referred to applies.
[1] l-ETS 300 245-2: "Integrated Services Digital Network (ISDN); Technical
characteristics of telephony terminals; Part 2: PCM A-law, handset telephony".
[2] I-ETS 300 480: "Public Switched Telephone Network (PSTN); Testing
specification for analogue handset telephony".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of this ETS, the following definitions apply:
additional receiving amplification: A facility provided in a terminal whereby the gain in the receiving
direction from telephone line to ear may be increased (or decreased), relative to that required by the
relevant terminal standard, for the purpose of enabling the user to select, within certain limits, his/her
preferred receiving loudness.
relevant terminal standard: A standard which would apply if the terminal concerned did not provide
additional receiving amplification for the benefit of hearing impaired users.
voice switching: A process of automatically inserting attenuation into either the send or receive path (e.g.
in order to maintain stability) controlled by the receive or send signal.
3.2 Abbreviations
For the purposes of this ETS, the following abbreviations apply:
AGC Automatic Gain Control
ERL Echo Return Loss
ISDN Integrated Services Digital Network
LSTR Listener Sidetone Rating
LRGP Loudness Rating Guardring Position
MRP Mouth Reference point
PSTN Public Switched Telephone Network
RLR Receiving Loudness Rating
SLR Sending Loudness Rating
STMR Sidetone Masking Rating
TCLw Weighted Terminal Coupling Loss
TE Terminal Equipment
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ETS 300 488: January 1996
4 Sending characteristics
4.1 General
The sending characteristics shall meet the requirements of the relevant terminal standards both with and
without additional receiving amplification selected.
4.2 Sensitivity frequency response
When in the sending condition, the sending sensitivity frequency response shall fulfil the requirements of
the relevant terminal standards, irrespective of any
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