ISO 16832:2006
(Main)Acoustics — Loudness scaling by means of categories
Acoustics — Loudness scaling by means of categories
ISO 16832:2006 specifies basic methods for scaling loudness into categories for audiological applications.
Acoustique — Mesurage de la sonie par échelles de catégories
General Information
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 16832
First edition
2006-08-01
Acoustics — Loudness scaling by means
of categories
Acoustique — Mesurage de la sonie par échelles de catégories
Reference number
ISO 16832:2006(E)
©
ISO 2006
---------------------- Page: 1 ----------------------
ISO 16832:2006(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall
not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the
unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.
© ISO 2006
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
©
ii ISO 2006 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 16832:2006(E)
Contents Page
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Category loudness scaling procedure . 2
5 Evaluation of the category loudness scaling . 4
6 Test report . 5
Annex A (informative) Example of a reference method . 6
Annex B (informative) Sample level sequences . 9
Annex C (informative) Illustration of loudness scales . 10
Bibliography . 11
©
ISO 2006 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 16832:2006(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International
Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 16832 was prepared by Technical Committee ISO/TC 43, Acoustics.
©
iv ISO 2006 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 16832:2006(E)
Introduction
The assessment of loudness function based on category loudness scaling is used when the evaluation of
hearing is not only necessary at the boundaries of the auditory sensation area (threshold of hearing,
uncomfortable level), but for a knowledge over the entire individual auditory sensation area.
Important fields of use are diagnostic evaluations, especially the evaluation of recruitment and fitting of hearing
instruments.
Since the results of loudness scaling can markedly depend on the exact procedure used, this International
Standard sets the conditions for reliable measurement methods.
©
ISO 2006 – All rights reserved v
---------------------- Page: 5 ----------------------
.
vi
---------------------- Page: 6 ----------------------
INTERNATIONAL STANDARD ISO 16832:2006(E)
Acoustics — Loudness scaling by means of categories
1Scope
This International Standard specifies basic methods for scaling loudness into categories for audiological
applications.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced document
(including any amendments) applies.
ISO 8253-1:1989, Acoustics — Audiometric test methods — Part 1: Basic pure tone air and bone conduction
threshold audiometry
ISO 8253-2:1992, Acoustics — Audiometric test methods — Part 2: Sound field audiometry with pure tone and
narrow-band test signals
IEC 60645-1:2001, Electroacoustsics — Audiological equipment — Part 1: Pure-tone audiometers
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
loudness
auditory sensation in terms of which sounds can be ordered on a scale extending from soft to loud
NOTE Loudness depends primarily upon the sound pressure of the stimulus, but also depends upon its frequency,
[4]
bandwidth, waveform and duration; see IEC 60050 .
3.2
category
one of an exhaustive set of classes among which loudness sensations can be distributed
3.3
category scale
ordering of a loudness sensation by means of categories
NOTE 1 The scale should contain a middle category and an equal number of categories above and below the middle
category.
NOTE 2 Perceptively equidistant categories should be used (for an example, see Annex A).
3.4
category loudness scaling
method whereby the test subject judges the loudness of a presented stimulus on a category scale
NOTE Verbal categories only describe loudness (for an example, see Annex A).
©
ISO 2006 – All rights reserved 1
---------------------- Page: 7 ----------------------
ISO 16832:2006(E)
3.5
response alternatives
choices available to the test subject in the rating scale
NOTE 1 The number of response alternatives may be larger than the number of categories on the category scale.
NOTE 2 If verbal categories are used, the number of response alternatives should be larger than the number of categories.
3.6
presentation level
sound pressure level at which the signal is presented
NOTE The number of presentation levels can be different from the number of categories and the number of response
alternatives.
3.7
dynamic range of hearing
difference between the highest stimulus level that is judged by the category “not heard” and the lowest stimulus
level that is judged by the category “extremely loud” for a specific auditory stimulus
3.8
auditory sensation field
region defined by the dynamic range of hearing across the audible frequency range
[4]
NOTE Because the auditory sensation area, according to IEC 60050 , is enclosed by the threshold of pain, the necessity
for the additional definition of the auditory sensation field was seen in order to define the actual measurement range.
3.9
loudness function
function describing the relation between the signal level and the corresponding loudness
3.10
familiarization
process of orienting the subject with the range of possible loudness magnitudes, the response alternatives and
the procedure
NOTE Within this range, stimuli are perceived absolutely with respect to their magnitude, i.e. without any perceived
relation, e.g. very loud or soft. The state of being familiarized may have its origin by past experience or actual presentation
of the range of loudness magnitudes.
4 Category loudness scaling procedure
4.1 General
The purpose of the category loudness scaling is to evaluate the loudness function of a test subject. Therefore,
signals with different levels are presented to the test subject who shall judge the loudness on a category scale.
The description of the scale can be verbal, numerical or symbolic. When verbal descriptions are used,
preferably, the name of the middle category is “medium”, the names of the boundary categories are “not heard”
and “extremely loud”. These categories can be transformed to a scale ranging, for example, from 0 to 50. In this
case, “0” on the scale corresponds to “not heard”, “25” corresponds to “medium” and “50” corresponds to
“extremely loud” (see Annex A).
©
2 ISO 2006 – All rights reserved
---------------------- Page: 8 ----------------------
ISO 16832:2006(E)
4.2 Procedure for assessment
4.2.1 Preparation and instruction of test subject
In the preparation and instruction of test subjects the requirements given in ISO 8253-1:1989, 5.1 and 5.2 apply.
For other conditions for the audiometric tests, follow the procedures given in ISO 8253-1:1989, Clause 4, as
applicable.
NOTE An example of the instruction is: “During the following examination you will hear signals (e.g. sounds, tones) that
differ in loudness (and pitch). Following each presentation, please indicate how loud the signal (the sound, the tone) is.”
In addition, the loudness categories shall be explained. The rating scale consisting of the response alternatives
shall be presented to the test subject during the test. The response alternatives shall contain at least all used
verbal or numerical categories. It should have provisions to make finer judgements between verbal categories.
Statistical analysis has shown that a minimum of 11 response alternatives is recommended.
4.2.2 Training and familiarization
The preparation and instruction is followed by a training and familiarization phase, in which the test subject
should hear levels over the whole dynamic range. This phase trains the subject and confirms the expectations
induced by the scale (between “not heard” and “extremely loud”). This phase avoids biases caused by the first
trials that do not cover the whole dynamic range. The phase ends when the test subject is judged to be ready
for a valid test.
4.2.3 Test
During the test, signals are presented to the test subject at all presentation levels. The range of presentation
levels should cover the individual dynamic range of hearing. An estimation of the dynamic range can be derived
from the results of the training phase (for an example, see Annex A).
After the presentation of a stimulus, the test subject shall indicate the loudness of the signal.
Each test signal shall be presented at at least five levels. These presentation levels shall be distinguishable and
should cover the whole dynamic range.
NOTE 1 In reasonable cases, exceptions can be made. Examples are tests with children or with test subjects with
extremely narrow residual dynamic range.
The presentation levels should be sequenced in a non-systematic way (pseudo-randomized). To avoid obtaining
judgements biased by the previous signal, two subsequent signals should be clearly different. These signals
should be as different as possible without confusing the test subjects (e.g. by variation of presentation level
and/or frequency). To ensure that the test subject stays familiarized during the whole test, the dynamic range of
hearing should be covered fully during short groups of subsequent presentations.
When the whole auditory sensation field is to be tested with narrow band signals, tests at at least four different
centre frequencies are required.
NOTE 2 Preferred standard centre frequencies are 500 Hz, 1kHz, 2kHz and 4kHz.
4.3 Test signal characteristics
The duration of the test signals shall be at least 1s. However, the signal may be switched off immediately if the
response of the test subject is “extremely loud”. The rise and fall times of the signal must comply with
IEC 60645-1:2001, 8.6.3.
In loudness scaling, narrow band signals shall be used. This includes filtered noise and warble tones. The
bandwidth of the signals shall not exceed one-third octave. To measure frequency-dependent effects, the filter
slope of the narrow band signals shall exceed 36 dB per octave. The filter slope of the test signals limits the
©
ISO 2006 – All rights reserved 3
---------------------- Page: 9 ----------------------
ISO 16832:2006(E)
application of the method. For subjects with steeply sloping hearing losses, a filter slope of at least 80 dB per
octave is recommended.
Whenever other signals are used, e.g. in cochlear-implant patients, they shall be specified in detail.
4.4 Test room and equipment
4.4.1 Transducers
Signal presentation may be via a loudspeaker, an earphone or, if neccessary, a cochlear implant.
4.4.2 Test room
For sound field audiometry, the ambient noise levels in the test room must comply with ISO 8253-2:1992,
Clause 6.
Sound field conditions shall be in accordance with ISO 8253-2:1992, Clause 5.
If pure tones are used in a free sound field, that sound field shall be in accordance with the specifications given
in ISO 8253-2:1992, 5.1.
For signal presentation via earphone, the test room shall comply with the requirements given in
ISO 8253-1:1989, 4.6.
4.4.3 Equipment
The test equipment shall comply with the general requirements given in IEC 60645-1:2001, Clause 5.
5 Evaluation of the category loudness scaling
5.1 Determination of reference values
To estimate a reference
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.