DS/EN ISO 6926:2016/A1:2020

Acoustics – Requirements for the performance and calibration of reference sound sources used for the determination of sound power levels – Amendment 1 (ISO 6926:2016/Amd 1:2020)

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This International Standard specifies the acoustical performance requirements for reference sound sources:
⎯ temporal steadiness (stability) of the sound power output,
⎯ spectral characteristics,
⎯ directivity.
Temporal steadiness is defined in terms of the standard deviation of repeatability (see 5.2). The performance
requirements on directivity index can only be verified in a hemi-anechoic room (see 5.5.) The spectral
characteristics can be verified in either a hemi-anechoic room or a reverberation test room from
measurements of the frequency band sound power levels according to this International Standard (see 5.4).
This International Standard also specifies procedures for providing level calibration data and uncertainty on a
sound source intended for use as a reference sound source in terms of its sound power level under reference
meteorological conditions as defined in Clause 4 in octave and in one-third octave bands, and with frequency
weighting A.
This International Standard is titled as a calibration standard even though the method is conducted in a test
laboratory and the level calibration results are not directly traceable to national standards of measure in a
strict metrological sense. Test laboratories performing this method, and users of the calibration data that
results from this method, are not expected to meet all requirements normally associated with a calibration
NOTE – ISO/IEC 17025[15] specifies different requirements for the competence of testing and calibration laboratories
respectively. Laboratories testing reference sound sources would typically comply with the requirements for testing
laboratories but not necessarily with those for calibration laboratories.
This International Standard specifies methods to calibrate reference sound sources not only in a free field over
a reflecting plane but also in reverberation test rooms at different distances from the boundary surfaces. For
the position of the reference sound source on one reflecting plane, the two different test environments
mentioned above are considered equivalent for frequency bands above or equal to 200 Hz. Below 200 Hz
some systematic differences may occur (see 11.2). For frequencies below 100 Hz an alternative calibration
method using sound intensity is given.
The sound source may either be placed directly on the floor or mounted on a stand to be used at a certain
elevation above the floor. According to this International Standard stand-mounted sources have to be
calibrated in reverberation test rooms. Floor-mounted sources can be calibrated both in hemi-anechoic and
reverberation test rooms. For floor-mounted sources in hemi-anechoic rooms, this International Standard is
valid only for sources whose maximum vertical dimension is less than 0,5 m and whose maximum horizontal
dimension is less than 0,8 m. According to this International Standard only floor-mounted reference sound
sources may be used when carrying out measurements on a measurement surface. For reference sound
sources to be used or calibrated under reverberant conditions, no such restrictions on maximum dimensions

Number of pages: 12

Published: 2020-12-11

Date of approval: 2020-12-07

International relationships : EN ISO 6926:2016/A1:2020 IDT ISO 6926:2016/Amd 1:2020 IDT

ICS: 17.140.01 - Acoustic measurements and noise abatement in general

Item number: M336347



  • CEN/TC 211
  • ISO/TC 43/SC 1
  • ISO/TC 43/SC 1/WG 28

Danish committee


Included in

  • Standardpakke - Akustik 4
    Standards Package – Acoustics 4 – Determination of sound power levels and sound energy levels of noise sources using sound pressure