ISO 9568:1993

INTERNATIONAL
IS0
STANDARD 9568
First edition
1993-01-I 5
- Background acoustic
Cinematography
noise levels in theatres, review rooms and
dubbing rooms
Niveaux de bruit de fond dans les sales de
Cinkmatographie -
projection, de visionnement et les auditoriums de doublage
Reference number
IS0 9568:1993(E)
IS0 9568:1993(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work
of preparing International Standards is normally carried out through IS0
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. IS0
collaborates closely with the International Electrotechnical Commission
(IEC) on all matters of electrotechnical standardization.
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.
International Standard IS0 9568 was prepared by Technical Committee
I SO/TC 36, Cinematography.
Annex A of this International Standard is for information only.
0 IS0 1993
All rights reserved. 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 per-
mission in writing from the publisher,
International Organization for Standardization
Case Postale 56 l CH-1211 Geneve 20 l Switzerland
Printed in Switzerland
ii
INTERNATIONAL STANDARD IS0 9568:1993(E)
Cinematography - Background acoustic noise levels
in theatres, review rooms and dubbing rooms
- Preferred frequencies for
IS0 266:1975, Acoustics
1 Scope
measurements.
This International Standard specifies measurement
I EC 651: 1979, Sound level meters.
methods and maximum ratings for indoor background
sound pressure levels in theatres, review rooms and
dubbing rooms.
3 Test conditions
It applies to noise emitted by heating, ventilating and
air-conditioning systems, intrusive noise from the
projector(s) associated with the theatre and noise
3.1 The air-handling system of the theatre shall be
emitted by any other mechanical or electrical equip-
brought to the noisiest state in which it is used during
ment in the theatre building. It is intended for appli-
screenings, generally “on”, with cooling compressors
cation when the background noise is essentially a
operating. Any other mechanical or electrical equip-
steady-state sound, without strong time-varying com-
ment, such as projector exhaust fans, sump pumps,
ponents.
transformers, or the like, within the theatre building
It does not apply to intrusive noise from other sources shall be brought to the noisiest state that will occur
outside the theatre, such as aircraft, highway traffic, during screenings. The projector system shall be run-
or adjacent theatres, or to noise resulting from the ning normally, with film. Power to the theatre sound
operation of the sound system in the theatre, or the system shall be turned off.
vibration of the theatre, i.e. movement of the building
below 20 Hz.
3.2 Measurement equipment shall conform to
IEC 651, using a class II octave band filter or class III
third-octave band filter in accordance with IS0 266.
2 Normative references 3.3 The measurement system shall be set to
“slow” reading.
The following standards contain provisions which,
through reference in this text, constitute provisions
of this International Standard. At the time of publica- 3.4 The measurement system shall be calibrated
tion, the editions indicated were valid. All standards immediately before use by means of an acoustic
calibrator accurate to within + 0,5 dB for sound
are subject to revision, and parties to agreements
pressure level. The calibration shall be checked after
based on this International Standard are encouraged
use, and if changes greater than 0,5 dB are found, the
to investigate the possibility of applying the most re-
measurements shall be considered invalid. The
cent editions of the standards indicated below.
acoustic calibrator shall be checked at least once per
Members of IEC and IS0 maintain registers of cur-
rently valid International Standards. year against a known source.

IS0 9568:1993(E)
3.5 At high frequencies, room background noise
4.2 The measurements to be recorded shall be
levels are often in the same range as ordinary
made by taking the mean of the readings at a suffi-
measurement equipment noise.
Therefore, care cient number of locations to provide means with
should be taken to ensure that the measured levels standard deviations under 2 dB; usually, six locations
are not influenced in any band by noise in the chosen at random within the seating area at seated
measurement instrument(s) by testing the measure- ear height at least 1,2 m (4 ft) from any wall surface
ment instrument(s) under all relevant conditions, in- will suffice unless there is an unusual spatial distri-
cluding switch settings of any attenuators or gain bution of background noise. If the total range of the
controls. Do not report noise levels at or below the measurements in an octave band is less than 4 dB,
capability of the instrumentation in use. t
...