Terminal Equipment (TE); Telephony for hearing impaired people; Characteristics of telephone sets that provide additional receiving amplification for the benefit of the hearing impaired

To specify extra audio amplification & related characteristics of telephony terminals to meet the need of hard-of-hearing people.

Terminalska oprema (TE) – Telefonija za slušno prizadete ljudi – Karakteristike telefonskih aparatov z dodatnim sprejemnim ojačevalnikom za pomoč slušno prizadetim

General Information

Status
Published
Publication Date
30-Nov-2003
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
01-Dec-2003
Due Date
01-Dec-2003
Completion Date
01-Dec-2003

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SIST ETS 300 488 E1:2003
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SLOVENSKI STANDARD
SIST ETS 300 488 E1:2003
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
SIST ETS 300 488 E1:2003 en

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

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SIST ETS 300 488 E1:2003
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SIST ETS 300 488 E1:2003
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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SIST ETS 300 488 E1:2003
Page 2
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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SIST ETS 300 488 E1:2003
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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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SIST ETS 300 488 E1:2003
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ETS 300 488: January 1996

History......................................................................................................................................................... 16

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SIST ETS 300 488 E1:2003
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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
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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