IEC 62489-1:2010/AMD1:2014

Amendment 1 - Electroacoustics - Audio-frequency induction loop systems for assisted hearing - Part 1: Methods of measuring and specifying the performance of system components

Amendement 1 - Electroacoustique - Systèmes de boucles d'induction audiofréquences pour améliorer l'audition - Partie 1: Méthodes de mesure et de spécification des performances des composants de systèmes

General Information

• Status: Published
• Publication Date: 16-Dec-2014
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 17.140.50 - Electroacoustics
• Technical Committee: TC 29 - Electroacoustics
• Drafting Committee: WG 22 - TC 29/WG 22
• Current Stage: PPUB - Publication issued
• Start Date: 31-Dec-2014
• Completion Date: 17-Dec-2014

Relations

• Amends: IEC 62489-1:2010 - Electroacoustics - Audio-frequency induction loop systems for assisted hearing - Part 1: Methods of measuring and specifying the performance of system components
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 62489-1 ®
Edition 1.0 2014-12
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
AM ENDMENT 1
AM ENDEMENT 1
Electroacoustics – Audio-frequency induction loop systems for assisted
hearing –
Part 1: Methods of measuring and specifying the performance of system
components
Électroacoustique – Systèmes de boucles d’induction audiofréquences pour
améliorer l'audition –
Partie 1: Méthodes de mesure et de spécification des performances des
composants de systèmes
IEC 62489-1:2010-01/AMD1:2014-12(en-fr)

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IEC 62489-1 ®
Edition 1.0 2014-12
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
AM ENDMENT 1
AM ENDEMENT 1
Electroacoustics – Audio-frequency induction loop systems for assisted

hearing –
Part 1: Methods of measuring and specifying the performance of system

components
Électroacoustique – Systèmes de boucles d’induction audiofréquences pour

améliorer l'audition –
Partie 1: Méthodes de mesure et de spécification des performances des

composants de systèmes
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
M
CODE PRIX
ICS 17.140.50 ISBN 978-2-8322-1957-7

– 2 – IEC 62489-1:2010/AMD1:2014
© IEC 2014
FOREWORD
This amendment has been prepared by IEC technical committee 29: Electroacoustics.
The text of this amendment is based on the following documents:
FDIS Report on voting
29/853/FDIS 29/860/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.
The committee has decided that the contents of this amendment and the base publication will
remain unchanged until the stability date indicated on the IEC web site under
"http://webstore.iec.ch" in the data related to the specific publication. At this date, the
publication 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.
_____________
CONTENTS
Add the titles of the new Clauses 9 and 10 and their subclauses as follows:
9 Neck loops
9.1 Input voltage
9.1.1 Characteristic to be specified
9.1.2 Method of measurement
9.2 Input impedance
9.2.1 Characteristic to be specified
9.2.2 Method of measurement
9.2.3 Recommended values
9.3 Frequency response
9.3.1 Characteristic to be specified
9.3.2 Method of measurement
9.3.3 Presentation of results
9.3.4 Connector
10 Monitoring devices
10.1 General
10.2 Recommendations for fixed devices
10.3 Recommendations for portable devices
Add the titles of the new Annexes D, E and F as follows.

© IEC 2014
Annex D (informative) Neck loops
Annex E (normative) Test jig for measuring the performance of neck loops
Annex F(normative) Specifications for loop listeners and assistive listening devices (ALDs)
Add, in the list of figures, the titles of new Figures E.1, E.2, E.3, E.4 and F.1 as follows.
Figure E.1 – Side view
Figure E.2 – Front view
Figure E.3 – Back view
Figure E.4 – Arrangement of the neck loop on the jig
Figure F.1 – Target frequency response
Add, in the list of tables, the title of the new Table 1, as follows.
Table 1 – Types of fixed monitoring device
2 Normative references
Add the following new references:
IEC 60417, Graphical symbols for use on equipment (available at http://www.graphical-
symbols.info/equipment)
IEC 60603-11, Connectors for frequencies below 3 MHz for use with printed boards – Part 11:
Detail specification for concentric connectors (dimensions for free connectors and fixed
connectors)
Replace the reference to "IEC 60268-3:2000", with the following updated reference:
IEC 60268-3:2013, Sound system equipment – Part 3: Amplifiers
3 Terms and definitions
Add, after 3.1 the following new terms and definitions:
3.2
phased loop array
system of neighbouring loops in which the currents are not in phase with each other
3.3
neck loop
small induction loop intended to be worn around the neck
NOTE See Annex D.
3.4
telecoil
magnetic pickup coil intended to receive signals from an induction-loop system in accordance
with IEC 60118-4
NOTE A telecoil can be part of a hearing aid or of any other device for receiving signals for an induction-loop
system in accordance with IEC 60118-4.

– 4 – IEC 62489-1:2010/AMD1:2014
© IEC 2014
3.5
loop listener
system consisting of a portable amplifier incorporating a telecoil and headphones or
earphones, intended to receive signals from an induction-loop system in accordance with
IEC 60118-4
NOTE The functions of loop listener and assistive listening device (see 3.6) can be combined.
3.6
assistive listening device
ALD
system consisting of a microphone, a portable amplifier and headphones, earphone or a neck
loop
NOTE 1 This device is not the portable receiver described in Annex E of IEC 60118-4:2006, which includes
measurement of magnetic field strength but no compensation for frequency-dependent hearing loss and AGC.
NOTE 2 This note applies to the French language only.
5.1 General
Replace, in the Note, the reference to IEC 60268-3:2000 with the updated reference to
IEC 606268-3:2013 as follows:
NOTE For characteristics not mentioned in this standard, the provisions of IEC 60268-3 can be applied, with the
provisions of 5.2 of this standard replacing those of 3.1 of IEC 60268-3:2013.
Add, after 5.4.13.3, the following new subclause:
5.4.13.4 Recommendations
It is strongly recommended that the amplifier should include automatic gain control with an
input level range of at least 32 dB for a maximum output level change of 3 dB. The total
harmonic distortion plus noise of the output current over this range should not exceed 5 %.
5.4.14 Phase error of quadrature networks for phased loop arrays
Replace all the existing subclauses by the following new subclauses:
5.4.14.1 Explanation
The primary means of reducing the overspill of the magnetic field of an AFILS to places where
it is not wanted is to reduce loop dimensions. If two or more adjacent small loops are
operated simultaneously in order to increase the useful magnetic field volume, the magnetic
fields partially or completely cancel in some places, creating unacceptable 'nulls', unless the
identical currents in the loops are decorrelated (forced to be 'out of step'). This can be
achieved in two ways:
• by delaying the current in one loop with respect to the other;
• by shifting the phase of the current in one loop by approximately 90° with respect to the
other.
The latter method is more commonly used. The phase difference needs to be near (but not
very precisely) 90°. The two fields create a rotating field (direction) vector, whose tip
describes a circle if the two fields are equal and at 90°. If not, it describes an ellipse, so that
the combined field is more irregular in space. If the two fields are not at 90° phase, one can
be considered as having a reference phase angle of 0°, the other having a relative phase
angle X. This field can be resolved into an in-phase component cos X and a quadrature
component sin X. The interaction of the in-phase component and the reference field tends to
produce the nulls in the vertical component of the field that would happen with no phase
difference. However, for small deviations from 90°, the effect is minimal. For example,

© IEC 2014
cos 85° = 0,087, so the in-phase field is increased or decreased by 0,72 dB, depending on
where the measurement is taken; in some places the fields add; in others they subtract.
5.4.14.2 Characteristic to be specified
The maximum deviation from 90° of the phase angle between the loop currents over the
frequency range 100 Hz to 5 kHz.
5.4.14.3 Method of measurement
See 14.11.4 of IEC 60268-3:2013. The loop currents may be measured by including a very
low value resistor in series with each loop and measuring the voltage across it. A 2-channel
audio analyser with balanced inputs may be used, or an oscilloscope. Because neither end of
the resistor is likely to be at earth potential, a simple balanced follower may be included
between the resistor and the input of the oscilloscope.
5.4.14.4 Presentation of results
The maximum deviation in degrees and the associated frequency or frequencies shall be
stated.
Insert, after Clause 6, the following new Clauses 9 and 10:
9 Neck loops
NOTE See Annex D for explanation and information and Annex B of IEC 60118-4:2006 for details of me
...