Table of Contents

3 -  AS 60118.2-2007 Hearing aids Part 2: Hearing aids with automatic gain control circuits
4 -  PREFACE
5 -  CONTENTS
7 -  1 Scope
7 -  2 Object
8 -  3 Conditions
8 -  3.1 General conditions
8 -  4 Explanation of terms
8 -  4.1 Automatic gain control ( AGC)
8 -  4.2 Steady- state input/ output graph
8 -  4.3 Lower AGC limit or AGC threshold
8 -  4.4 Compression ratio ( between specified input sound pressure level values)
8 -  4.5 Dynamic output characteristics
8 -  4.6 Attack time
8 -  4.6.1 Attack time for the normal dynamic range of speech
9 -  4.6.2 High level attack time
9 -  4.7 Recovery time
9 -  4.7.1 Recovery time for the normal dynamic range of speech
9 -  4.7.2 High level recovery time
9 -  4.8 AGC activated frequency response
9 -  4.9 Operating frequency range of the AGC
9 -  4.10 Overall root- mean- square sound pressure level ( overall r. m. s. SPL)
9 -  4.11 One- third- octave band level
9 -  4.12 Auto- spectrum ( power spectrum)
9 -  4.13 Cross- spectrum ( GAB)
10 -  4.14 Coherence
10 -  4.15 Synchronous analysis
10 -  5 Steady- state input/ output graph
10 -  5.1
10 -  5.2 Methods of measurement
10 -  6 Dynamic output characteristics
10 -  6.1 Characteristics to be measured
11 -  6.2 Methods of measurement
11 -  6.2.1 Dynamic output characteristics for speech levels
11 -  6.2.2 Dynamic output characteristics for high level input
11 -  7 Non- linear distortion
11 -  7.1 Transients
11 -  7.2 Harmonic distortion
11 -  7.2.1 Characteristics to be specified
11 -  7.2.2 Methods of measurement
12 -  7.3 Intermodulation distortion
12 -  8 Effect on steady- state and dynamic performance with respect to variation in battery or supply voltage
12 -  9 AGC activated frequency response of hearing aids with a single channel
12 -  9.1 Introduction
12 -  9.2 General conditions
12 -  9.3 Test equipment
13 -  9.4 Test conditions
13 -  9.5 Measurement
13 -  9.5.1 Determination of the operating range of the AGC
13 -  9.5.2 Measurement of the AGC activated frequency response
14 -  9.6 Frequency response recording chart
14 -  10 Frequency response of hearing aids with AGC circuits in operation
14 -  10.1 General
15 -  10.2 Test enclosure
15 -  10.3 Test conditions
15 -  10.3.1 Noise input signal
16 -  10.4 Test equipment
17 -  10.5 Measurements of frequency responses
17 -  10.5.1 Comprehensive frequency responses and basic frequency response ( acoustic gain)
17 -  10.5.1.1 Cross- spectrum method
17 -  10.5.1.2 Auto- spectrum method
18 -  10.5.1.3 Swept filter method
18 -  10.6 Frequency response recording chart
19 -  Annex A (informative) Examples of measuring systems
22 -  Annex B (informative) Smoothed data presentation
23 -  Annex C (informative) Bibliography

Abstract

Adopts IEC 60118-2 to apply to hearing aids of any type with automatic gain control (AGC) circuits.

General Product Information

Published
Document Type	Standard
Status	Current
Publisher	Standards Australia
Pages
ISBN
Committee	AV-003
Supersedes	AS 1088.2-1987 DR 06467 CP