ISO 17497-1:2004
(Main)Acoustics — Sound-scattering properties of surfaces — Part 1: Measurement of the random-incidence scattering coefficient in a reverberation room
Acoustics — Sound-scattering properties of surfaces — Part 1: Measurement of the random-incidence scattering coefficient in a reverberation room
ISO 17497-1:2004 specifies a method of measuring the random-incidence scattering coefficient of surfaces as caused by surface roughness. The measurements are made in a reverberation room, either in full scale or on a physical scale model. The measurement results can be used to describe how much the sound reflection from a surface deviates from a specular reflection. The results obtained can be used for comparison purposes and for design calculations with respect to room acoustics and noise control. The method is not intended for characterizing the spatial uniformity of the scattering from a surface.
Acoustique — Propriétés de dispersion du son par les surfaces — Partie 1: Mesurage du coefficient de dispersion sous incidence aléatoire en salle réverbérante
General Information
Relations
Buy Standard
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 17497-1
First edition
2004-05-01
Acoustics — Sound-scattering properties
of surfaces —
Part 1:
Measurement of the random-incidence
scattering coefficient in a reverberation
room
Acoustique — Propriétés de dispersion du son par les surfaces —
Partie 1: Mesurage du coefficient de dispersion sous incidence
aléatoire en salle réverbérante
Reference number
©
ISO 2004
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 2004
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 2004 – All rights reserved
Contents Page
Foreword. iv
Introduction . v
1 Scope. 1
2 Normative references . 1
3 Terms and definitions. 1
4 Principle . 2
5 Frequency range . 3
6 Test arrangement. 4
6.1 Reverberation room. 4
6.2 Turntable and base plate. 4
6.3 Test sample . 5
7 Test procedure . 6
7.1 Test signals . 6
7.2 Source and receiving equipment . 7
7.3 Measurement of impulse responses. 7
7.4 Temperature and relative humidity . 7
7.5 Evaluation of decay curves. 7
8 Expression of results. 8
8.1 Method of calculation . 8
8.2 Precision . 9
8.3 Presentation of results . 10
9 Test report . 10
Annex A (informative) Accuracy of the measurement results. 11
Bibliography . 12
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 17497-1 was prepared by Technical Committee ISO/TC 43, Acoustics, Subcommittee SC 2, Building
acoustics.
ISO 17497 consists of the following parts, under the general title Acoustics — Sound-scattering properties of
surfaces:
Part 1: Measurement of the random-incidence scattering coefficient in a reverberation room
The following part is under preparation:
Part 2: Measurement of the directional diffusion coefficient in a free field
iv © ISO 2004 – All rights reserved
Introduction
The degree of acoustic scattering from surfaces is very important in all aspects of room acoustics (e.g. in
concert halls, sound studios, industrial halls and reverberation chambers). Insufficient scattering may cause
strong deviations from exponential sound pressure decay. On the other hand, an approximately diffuse sound
field may be obtained with highly scattering surfaces in a room. The degree of scattering in a room can be an
important factor related to the acoustic quality of the room.
The scattering coefficient is introduced as a new concept in this part of ISO 17497. Together with the
absorption coefficient, the scattering coefficient will be useful in room acoustic calculations, simulations and
prediction models. For some time it has been known that modelling of the scattering from surfaces is very
important for obtaining reliable predictions of room acoustics. This part of ISO 17497 presents a measurement
method to quantify the scattering properties of a surface to replace formerly applied but not generally
accepted estimation methods.
The work has been coordinated with the working group of the Audio Engineering Society, AES SC-04-02 for
the Characterization of Acoustical Materials. This group emphasized the development of a measurement
method for the directional diffusion coefficient, which is different from (but related to) the random incidence
scattering coefficient. While the scattering coefficient is a rough measure that describes the degree of
scattered sound, the diffusion coefficient describes the directional uniformity of the scattering; i.e. the quality of
the diffusing surface. Therefore there is a need for both concepts and they have different applications.
INTERNATIONAL STANDARD ISO 17497-1:2004(E)
Acoustics — Sound-scattering properties of surfaces —
Part 1:
Measurement of the random-incidence scattering coefficient in
a reverberation room
1 Scope
This part of ISO 17497 specifies a method of measuring the random-incidence scattering coefficient of
surfaces as caused by surface roughness. The measurements are made in a reverberation room, either in full
scale or on a physical scale model. The measurement results can be used to describe how much the sound
reflection from a surface deviates from a specular reflection. The results obtained can be used for comparison
purposes and for design calculations with respect to room acoustics and noise control.
The method is not intended for characterizing the spatial uniformity of the scattering from a surface.
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 354, Acoustics — Measurement of sound absorption in a reverberation room
ISO 9613-1, Acoustics — Attenuation of sound during propagation outdoors — Part 1: Calculation of the
absorption of sound by the atmosphere
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 354 and the following apply.
3.1
specular reflection
reflection that obeys Snell’s law, i.e. the angle of reflection is equal to the angle of incidence
NOTE Specular reflection can be obtained approximately from a plane, rigid surface with dimensions much larger
than the wavelength of the incident sound.
3.2
diffuse sound field
sound field in which the incident sound intensity on a plane surface is equally distributed over all solid angles
covering a hemisphere
3.3
scattering coefficient
s
θ
value calculated by one minus the ratio of the specularly reflected acoustic energy to the total reflected
acoustic energy
NOTE Theoretically, s can take values between 0 and 1, where 0 means a totally specularly reflecting surface, and 1
θ
means a totally scattering surface. The subscript θ may be used to indicate the angle of incidence relative to the normal of
the surface. Random incidence is understood if there is no subscript.
3.4
random-incidence scattering coefficient
s
value calculated by one minus the ratio of the specularly reflected acoustic energy to the total acoustic energy
reflected from a surface in a diffuse sound field
3.5
random-incidence absorption coefficient
α
s
value calculated by one minus the ratio of the total reflected acoustic energy to the incident acoustic energy,
on a surface in a diffuse sound field
3.6
random-incidence specular absorption coefficient
α
spec
value calculated by one minus the ratio of the specularly reflected acoustic energy to the incident acoustic
energy, on a surface in a diffuse sound field
NOTE This is the apparent absorption coefficient when the losses include the scattered as well as the absorbed
acoustic energy. α may take values in the range from α to 1.
spec s
3.7
physical scale ratio
1:N
ratio of any linear dimension in a physical scale model to the same linear dimension in full scale
NOTE The wavelength of the sound used in a scale model for acoustic measurements obeys the same physical
scale ratio. So, if the speed of sound is the same in the model as in full scale, the frequencies used for the model
measurements will be a factor of N times higher than those in full scale.
4 Principle
The general principle of the method can best be explained by looking at the effect of reflection and scattering
in the time domain. Figure 1 shows three bandpass-filtered pulses which were reflected from a corrugated
surface for different orientations of the test sample in the free field.
2 © ISO 2004 – All rights reserved
Key
p sound pressure, in pascals
t time, in milliseconds
Figure 1 — Examples of band-pass filtered impulse responses measured at three different positions
of the test sample
Obviously, the initial parts of the reflections are highly correlated. This coherent part is identical with the
specular component of the reflection. In contrast, the later parts are not in phase and depend strongly on the
specific orientation. The energy in the “tail” of the reflected pulse contains the scattered part.
The principle of the measurement method is to extract the specular energy from the reflected pulses. This is
done by synchronized (phase-locked) averaging of the impulse responses obtained for different sample
orientations.
The principle can be directly applied to measurements in the reverberation room. In addition to conventional
measurements of absorption coefficient, the (circular) sample is placed on a turntable and impulse responses
are obtained for different sample orientations. By synchronized averaging of the pressure impulse responses,
the specular components add up in phase, whereas the scattered sound interferes destructively.
Assuming statistical independence between scattered components, it can be shown (see [1]) that after
synchronized addition of n room impulse respon
...
INTERNATIONAL ISO
STANDARD 17497-1
First edition
2004-05-01
Acoustics — Sound-scattering properties
of surfaces —
Part 1:
Measurement of the random-incidence
scattering coefficient in a reverberation
room
Acoustique — Propriétés de dispersion du son par les surfaces —
Partie 1: Mesurage du coefficient de dispersion sous incidence
aléatoire en salle réverbérante
Reference number
©
ISO 2004
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 2004
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 2004 – All rights reserved
Contents Page
Foreword. iv
Introduction . v
1 Scope. 1
2 Normative references . 1
3 Terms and definitions. 1
4 Principle . 2
5 Frequency range . 3
6 Test arrangement. 4
6.1 Reverberation room. 4
6.2 Turntable and base plate. 4
6.3 Test sample . 5
7 Test procedure . 6
7.1 Test signals . 6
7.2 Source and receiving equipment . 7
7.3 Measurement of impulse responses. 7
7.4 Temperature and relative humidity . 7
7.5 Evaluation of decay curves. 7
8 Expression of results. 8
8.1 Method of calculation . 8
8.2 Precision . 9
8.3 Presentation of results . 10
9 Test report . 10
Annex A (informative) Accuracy of the measurement results. 11
Bibliography . 12
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 17497-1 was prepared by Technical Committee ISO/TC 43, Acoustics, Subcommittee SC 2, Building
acoustics.
ISO 17497 consists of the following parts, under the general title Acoustics — Sound-scattering properties of
surfaces:
Part 1: Measurement of the random-incidence scattering coefficient in a reverberation room
The following part is under preparation:
Part 2: Measurement of the directional diffusion coefficient in a free field
iv © ISO 2004 – All rights reserved
Introduction
The degree of acoustic scattering from surfaces is very important in all aspects of room acoustics (e.g. in
concert halls, sound studios, industrial halls and reverberation chambers). Insufficient scattering may cause
strong deviations from exponential sound pressure decay. On the other hand, an approximately diffuse sound
field may be obtained with highly scattering surfaces in a room. The degree of scattering in a room can be an
important factor related to the acoustic quality of the room.
The scattering coefficient is introduced as a new concept in this part of ISO 17497. Together with the
absorption coefficient, the scattering coefficient will be useful in room acoustic calculations, simulations and
prediction models. For some time it has been known that modelling of the scattering from surfaces is very
important for obtaining reliable predictions of room acoustics. This part of ISO 17497 presents a measurement
method to quantify the scattering properties of a surface to replace formerly applied but not generally
accepted estimation methods.
The work has been coordinated with the working group of the Audio Engineering Society, AES SC-04-02 for
the Characterization of Acoustical Materials. This group emphasized the development of a measurement
method for the directional diffusion coefficient, which is different from (but related to) the random incidence
scattering coefficient. While the scattering coefficient is a rough measure that describes the degree of
scattered sound, the diffusion coefficient describes the directional uniformity of the scattering; i.e. the quality of
the diffusing surface. Therefore there is a need for both concepts and they have different applications.
INTERNATIONAL STANDARD ISO 17497-1:2004(E)
Acoustics — Sound-scattering properties of surfaces —
Part 1:
Measurement of the random-incidence scattering coefficient in
a reverberation room
1 Scope
This part of ISO 17497 specifies a method of measuring the random-incidence scattering coefficient of
surfaces as caused by surface roughness. The measurements are made in a reverberation room, either in full
scale or on a physical scale model. The measurement results can be used to describe how much the sound
reflection from a surface deviates from a specular reflection. The results obtained can be used for comparison
purposes and for design calculations with respect to room acoustics and noise control.
The method is not intended for characterizing the spatial uniformity of the scattering from a surface.
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 354, Acoustics — Measurement of sound absorption in a reverberation room
ISO 9613-1, Acoustics — Attenuation of sound during propagation outdoors — Part 1: Calculation of the
absorption of sound by the atmosphere
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 354 and the following apply.
3.1
specular reflection
reflection that obeys Snell’s law, i.e. the angle of reflection is equal to the angle of incidence
NOTE Specular reflection can be obtained approximately from a plane, rigid surface with dimensions much larger
than the wavelength of the incident sound.
3.2
diffuse sound field
sound field in which the incident sound intensity on a plane surface is equally distributed over all solid angles
covering a hemisphere
3.3
scattering coefficient
s
θ
value calculated by one minus the ratio of the specularly reflected acoustic energy to the total reflected
acoustic energy
NOTE Theoretically, s can take values between 0 and 1, where 0 means a totally specularly reflecting surface, and 1
θ
means a totally scattering surface. The subscript θ may be used to indicate the angle of incidence relative to the normal of
the surface. Random incidence is understood if there is no subscript.
3.4
random-incidence scattering coefficient
s
value calculated by one minus the ratio of the specularly reflected acoustic energy to the total acoustic energy
reflected from a surface in a diffuse sound field
3.5
random-incidence absorption coefficient
α
s
value calculated by one minus the ratio of the total reflected acoustic energy to the incident acoustic energy,
on a surface in a diffuse sound field
3.6
random-incidence specular absorption coefficient
α
spec
value calculated by one minus the ratio of the specularly reflected acoustic energy to the incident acoustic
energy, on a surface in a diffuse sound field
NOTE This is the apparent absorption coefficient when the losses include the scattered as well as the absorbed
acoustic energy. α may take values in the range from α to 1.
spec s
3.7
physical scale ratio
1:N
ratio of any linear dimension in a physical scale model to the same linear dimension in full scale
NOTE The wavelength of the sound used in a scale model for acoustic measurements obeys the same physical
scale ratio. So, if the speed of sound is the same in the model as in full scale, the frequencies used for the model
measurements will be a factor of N times higher than those in full scale.
4 Principle
The general principle of the method can best be explained by looking at the effect of reflection and scattering
in the time domain. Figure 1 shows three bandpass-filtered pulses which were reflected from a corrugated
surface for different orientations of the test sample in the free field.
2 © ISO 2004 – All rights reserved
Key
p sound pressure, in pascals
t time, in milliseconds
Figure 1 — Examples of band-pass filtered impulse responses measured at three different positions
of the test sample
Obviously, the initial parts of the reflections are highly correlated. This coherent part is identical with the
specular component of the reflection. In contrast, the later parts are not in phase and depend strongly on the
specific orientation. The energy in the “tail” of the reflected pulse contains the scattered part.
The principle of the measurement method is to extract the specular energy from the reflected pulses. This is
done by synchronized (phase-locked) averaging of the impulse responses obtained for different sample
orientations.
The principle can be directly applied to measurements in the reverberation room. In addition to conventional
measurements of absorption coefficient, the (circular) sample is placed on a turntable and impulse responses
are obtained for different sample orientations. By synchronized averaging of the pressure impulse responses,
the specular components add up in phase, whereas the scattered sound interferes destructively.
Assuming statistical independence between scattered components, it can be shown (see [1]) that after
synchronized addition of n room impulse respon
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.