IEC 60268-24:2023

Sound system equipment - Part 24: Headphones and earphones - Active acoustic noise cancelling characteristics

IEC 60268-24:2023 is applicable to active acoustic noise-cancelling headphones and earphones which have the function of reducing the noise heard by the user by the output sound from the transducer generated by the environment noise detection microphone and the noise reduction signal processing circuit.
This document specifies the terms and definitions of this type of headphones or earphones, the characteristics to be specified, and the measurement and evaluation methods.
The noise detection microphone or microphones are mounted in the body, on the surface, or on an accessory of the headphones or earphones. Signal processing circuits are analogue and digital electronic circuits.
This document does not deal with equipment intended for hearing protection.
The noise cancelling characteristic measurement methods can be applied to headphones and earphones having no active noise cancelling function.

Equipements pour systèmes électroacoustiques - Partie 24: Casques et écouteurs - Caractéristiques d'annulation active du bruit acoustique

L'IEC 60268-24:2023 s'applique aux casques et écouteurs à annulation active du bruit acoustique qui ont pour fonction de réduire le bruit entendu par l'utilisateur; le son obtenu en sortie provient du transducteur et il est généré par le microphone de détection du bruit ambiant et le circuit de traitement du signal de réduction du bruit.
Le présent document spécifie les termes et définitions relatifs à ce type de casques ou d'écouteurs, les caractéristiques à spécifier ainsi que les méthodes de mesurage et d'évaluation.
Le microphone ou les microphones de détection du bruit sont montés à l'intérieur du corps, sur la surface ou sur un accessoire des casques ou des écouteurs. Les circuits de traitement du signal sont des circuits électroniques analogiques et numériques.
Le présent document ne traite pas des équipements destinés à la protection auditive.
Les méthodes de mesurage des caractéristiques d'annulation du bruit peuvent être appliquées aux casques et aux écouteurs qui n'ont aucune fonction d'annulation active du bruit.

General Information

• Status: Published
• Publication Date: 29-Nov-2023
• ICS: 33.160.01 - Audio, video and audiovisual systems in general
• Technical Committee: TA 20 - Analogue and digital audio
• Drafting Committee: PT 60268-24 - TC 100/TA 20/PT 60268-24
• Current Stage: PPUB - Publication issued
• Start Date: 25-Dec-2023
• Completion Date: 30-Nov-2023

Standards Content (Sample)

IEC 60268-24 ®
Edition 1.0 2023-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Sound system equipment –
Part 24: Headphones and earphones – Active acoustic noise cancelling
characteristics
Équipements pour systèmes électroacoustiques –
Partie 24: Casques et écouteurs – Caractéristiques d'annulation active du bruit
acoustique
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IEC 60268-24 ®
Edition 1.0 2023-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Sound system equipment –
Part 24: Headphones and earphones – Active acoustic noise cancelling

characteristics
Équipements pour systèmes électroacoustiques –

Partie 24: Casques et écouteurs – Caractéristiques d'annulation active du bruit

acoustique
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.160.01  ISBN 978-2-8322-7882-6

– 2 – IEC 60268-24:2023 © IEC 2023
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 8
4 Measurement method for noise cancelling characteristics . 9
4.1 Characteristics to be specified . 9
4.2 Test signals . 10
4.2.1 Pink noise . 10
4.2.2 Simulated ambient noise . 10
4.3 Nominal environmental conditions . 13
4.3.1 General . 13
4.3.2 Test site . 13
4.3.3 Background noise . 13
4.4 Test equipment . 14
4.4.1 Playback equipment for test signals . 14
4.4.2 Acoustic test equipment . 14
4.4.3 Analysis equipment. 14
4.5 Test procedure for measurement of noise suppression level . 15
4.5.1 Adjustment of sound pressure level of test signals . 15
4.5.2 Sound pressure level measurement at HP-OFF condition . 15
4.5.3 Sound pressure level measurement at ANC-OFF condition . 15
4.5.4 Sound pressure level measurement at ANC-ON condition. 15
4.6 Test procedure for measurement of noise suppression loudness. 16
4.6.1 Adjustment of loudness of test signals . 16
4.6.2 Loudness measurement at HP-OFF condition . 16
4.6.3 Loudness measurement at ANC-OFF condition . 16
4.6.4 Loudness measurement at ANC-ON condition . 16
4.7 Reporting of data . 16
4.7.1 Insertion Loss . 16
4.7.2 Noise suppression ratio . 17
Annex A (normative) Pseudo-diffuse sound field for measurement of ANC headphones . 18
Annex B (informative) Example of reporting of data . 20
Annex C (informative) Examples of filter circuits for making simulated ambient noise . 22
Annex D (informative) Procedure for real ear measurements . 24
Bibliography . 25

Figure 1 – Tolerance limit of power spectrum of simulated aircraft cabin noise . 11
Figure 2 – Tolerance limit of power spectrum of simulated train compartment noise . 12
Figure 3 – Tolerance limit of power spectrum of simulated cafeteria noise . 13
Figure 4 – Example of noise-cancelling characteristic measurement system . 15
Figure A.1 – Measurement reference point and sound pressure level confirmation point . 18
Figure B.1 – Example of reporting of insertion loss performance . 20
Figure C.1 – Example of filter circuit for making simulated aircraft cabin noise. 22
Figure C.2 – Example of filter circuit for making simulated train compartment noise . 23

Table 1 – Power spectrum of simulated aircraft cabin noise . 10
Table 2 – Power spectrum of simulated train compartment noise . 11
Table 3 – Power spectrum of simulated cafeteria noise . 12
Table B.1 – Example of reporting of insertion loss performance . 21
Table B.2 – Example of reporting of noise suppression ratio performance . 21

– 4 – IEC 60268-24:2023 © IEC 2023
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SOUND SYSTEM EQUIPMENT –
Part 24: Headphones and earphones –
Active acoustic noise cancelling characteristics

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