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Technical
Specification
ISO/TS 19425
Second edition
Reciprocating internal combustion
2024-07
engines — Measurement method
for air cleaners — Sound power
level of combustion air inlet noise
and insertion loss using sound
pressure
Moteurs alternatifs à combustion interne — Méthode de mesure
du bruit des purificateurs d'air — Niveau de puissance sonore du
bruit d'entrée d'air de combustion et de perte d'insertion utilisant
une pression sonore
Reference number
© ISO 2024
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ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Test environment . 5
4.1 General .5
4.2 Criterion for background noise.5
4.3 Criterion for acoustic adequacy of test environment .6
5 Instrumentation . 6
5.1 General .6
5.2 Calibration .6
5.3 Application .7
6 Installation and operation conditions . 7
6.1 General .7
6.2 Installation condition .7
6.3 Operation condition .8
7 Measurement . 9
7.1 General .9
7.2 Measurement uncertainty .9
7.3 Characteristic source dimension .10
7.4 Measurement radius .10
7.5 Measurement surface and area .10
7.6 Microphone arrays .10
8 Calculation .12
8.1 General . 12
8.2 Calculation of sound power level. 12
8.2.1 Mean time-averaged sound pressure levels . 12
8.2.2 Corrections for background noise . 13
8.2.3 Corrections for environmental . 13
8.2.4 Surface time-averaged sound pressure levels .14
8.2.5 Sound power levels .14
8.3 Calculation of insertion loss .14
9 Information to be recorded .15
10 Test report .16
Annex A (normative) Qualification procedures for the acoustic environment . 17
Annex B (normative) Calculation of A-weighted sound power levels from frequency band levels .20
Annex C (normative) Sound power level under reference meteorological conditions .22
Bibliography .23
iii
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
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The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
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This document was prepared by Technical Committee ISO/TC 70, Air-borne noise.
This second edition cancels and replaces the first edition (ISO 19425:2015), which has been technically
revised.
The main changes are as follows:
— the terms and definitions have been revised and sources have been added (see Clause 3);
— the criterion for background noise has been changed (see 4.2);
— the application has been changed (see 5.3);
— the installation condition has been changed (see 6.2);
— the operation condition has been changed (see 6.3);
— the measurement radius has been changed (see 7.4).
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
Technical Specification ISO/TS 19425:2024(en)
Reciprocating internal combustion engines — Measurement
method for air cleaners — Sound power level of combustion
air inlet noise and insertion loss using sound pressure
1 Scope
This document specifies the measurement method and requirements for combustion air inlet noise of
air cleaners which are installed on reciprocating internal combustion engines, including laboratory
measurement (engineering method and survey method) and site measurement (survey method).
This document applies to all air cleaners installed on reciprocating internal combustion engines
(reciprocating internal combustion engine is referred to as engine hereafter, except for specific explanations)
falling within the field of application of ISO 3046-1 and/or other air induction installation.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 3046-1, Reciprocating internal combustion engines — Performance — Part 1: Declarations of power, fuel
and lubricating oil consumptions, and test methods — Additional requirements for engines for general use
ISO 3046-3, Reciprocating internal combustion engines — Performance — Part 3: Test measurements
ISO 6926, Acoustics — Requirements for the performance and calibration of reference sound sources used for
the determination of sound power levels
IEC 60942, Electroacoustics — Sound calibrators
IEC 61260, Electroacoustics — Octave-band and fractional-octave-band filters
IEC 61672-1, Electroacoustics — Sound level meters—Part 1: Specifications
3 Terms and definitions
For the purposes of this document, the terms and definitions defined in ISO 3046-1, ISO 3046-3, ISO 6926,
IEC 60942, IEC 61260 and IEC 61672-1 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
sound pressure
p
difference between instantaneous pressure and static pressure
Note 1 to entry: It is expressed in pascals.
[SOURCE: ISO 80000-8:2007, 8-9.2]
3.2
sound pressure level
L
p
ten times the logarithm to the base 10 of the ratio of the square of the sound pressure (3.1), p, to the square of
a reference value, p
p
L =10lg
p
p
where the reference value, p , is 20 μPa
Note 1 to entry: If specific frequency and time weightings, as specified in IEC
...