SIST ISO 1996-2:2007

INTERNATIONAL ISO
STANDARD 1996-2
Second edition
2007-03-15
Acoustics — Description, measurement
and assessment of environmental
noise —
Part 2:
Determination of environmental noise
levels
Acoustique — Description, évaluation et mesurage du bruit de
l'environnement —
Partie 2: Détermination des niveaux de bruit de l'environnement

Reference number
©
ISO 2007
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ii © ISO 2007 – All rights reserved

Contents Page
Foreword. v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 2
4 Measurement uncertainty . 2
5 Instrumentation. 3
5.1 Instrumentation system . 3
5.2 Calibration . 3
6 Operation of the source . 4
6.1 General. 4
6.2 Road traffic . 4
6.3 Rail traffic . 5
6.4 Air traffic . 5
6.5 Industrial plants . 5
6.6 Low-frequency sound sources. 6
7 Weather conditions. 6
7.1 General. 6
7.2 Conditions favourable to sound propagation. 6
7.3 Average sound pressure levels under a range of weather conditions . 7
8 Measurement procedure . 7
8.1 Principle. 7
8.2 Selection of measurement time interval. 7
8.3 Microphone location. 7
8.4 Measurements. 9
9 Evaluation of the measurement result. 10
9.1 General. 10
9.2 Time-integrated levels, L and L . 11
E eqT
9.3 Maximum level, L . 11
max
9.4 Exceedance levels, L . 12
N,T
9.5 Indoor measurements . 12
9.6 Residual sound . 13
10 Extrapolation to other conditions . 13
10.1 Location . 13
10.2 Other time and operating conditions. 13
11 Calculation. 14
11.1 General. 14
11.2 Calculation methods. 14
12 Information to be recorded and reported.15
Annex A (informative) Meteorological window and measurement uncertainty due to weather . 16
Annex B (informative) Microphone positions relative to reflecting surfaces . 23
Annex C (informative) Objective method for assessing the audibility of tones in noise —
Reference method. 27
Annex D (informative) Objective method for assessing the audibility of tones in noise —
Simplified method . 36
Annex E (informative) National source-specific calculation methods. 37
Bibliography . 40

iv © ISO 2007 – All rights reserved

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 1996-2 was prepared by Technical Committee ISO/TC 43, Acoustics, Subcommittee SC 1, Noise.
This second edition of ISO 1996-2, together with ISO 1996-1:2003, cancels and replaces the first edition
(ISO 1996-2:1987), ISO 1996-1:1982 and ISO 1996-3:1987. It also incorporates the Amendment
ISO 1996-2:1987/Amd.1:1998.
ISO 1996 consists of the following parts, under the general title Acoustics — Description, measurement and
assessment of environmental noise:
⎯ Part 1: Basic quantities and assessment procedures
⎯ Part 2: Determination of environmental noise levels

INTERNATIONAL STANDARD ISO 1996-2:2007(E)

Acoustics — Description, measurement and assessment of
environmental noise —
Part 2:
Determination of environmental noise levels
1 Scope
This part of ISO 1996 describes how sound pressure levels can be determined by direct measurement, by
extrapolation of measurement results by means of calculation, or exclusively by calculation, intended as a
basis for assessing environmental noise. Recommendations are given regarding preferable conditions for
measurement or calculation to be applied in cases where other regulations do not apply. This part of ISO 1996
can be used to measure with any frequency weighting or in any frequency band. Guidance is given to
evaluate the uncertainty of the result of a noise assessment.
NOTE 1 As this part of ISO 1996 deals with measurements under actual operating conditions, there is no relationship
between this part of ISO 1996 and other ISO standards specifying emission measurements under specified operating
conditions.
NOTE 2 For the sake of generality, the frequency and time weighting subscripts have been omitted throughout this part
of ISO 1996.
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 1996-1:2003, Acoustics — Description, measurement and assessment of environmental noise —
Part 1: Basic quantities and assessment procedures
ISO 7196, Acoustics — Frequency-weighting characteristic for infrasound measurements
IEC 60942:2003, Electroacoustics — Sound calibrators
IEC 61260:1995, Electroacoustics — Octave-band and fractional-octave band filters
IEC 61672-1:2002, Electroacoustics — Sound level meters — Part 1: Specifications
Guide to the expression of uncertainty in measurement (GUM), BIPM/IEC/IFCC/ISO/IUPAC/IUPAP/OIML,
1993 (corrected and reprinted, 1995)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 1996-1 and the following apply.
3.1
receiver location
location at which the noise is assessed
3.2
calculation method
set of algorithms to calculate the sound pressure level at arbitrary locations from measured or predicted sound
emission and sound attenuation data
3.3
prediction method
subset of a calculation method, intended for the calculation of future noise levels
3.4
measurement time interval
time interval during which a single measurement is conducted
3.5
observation time interval
time interval during which a series of measurements is conducted
3.6
meteorological window
set of weather conditions during which measurements can be performed with limited and known variation in
measurement results due to weather variation
3.7
soundpath radius of curvature
R
radius approximating the curvature of the sound paths due to atmospheric refraction
NOTE R is expressed in kilometres.
3.8
low-frequency sound
sound containing frequencies of interest within the range covering the one-third octave bands from 16 Hz to
200 Hz
4 Measurement uncertainty
The uncertainty of sound pressure levels determined as described in this part of ISO 1996 depends on the
sound source and the measurement time interval, the weather conditions, the distance from the source and
the measurement method and instrumentation. The measurement uncertainty shall be determined in
accordance with the GUM. Some guidelines on how to estimate the measurement uncertainty are given in
Table 1, where the measurement uncertainty is expressed as an expanded uncertainty based on a combined
standard uncertainty multiplied by a coverage factor of 2, providing a coverage probability of approximately
95 %. Table 1 refers to A-weighted equivalent continuous sound pressure levels only. Higher uncerta
...