EN ISO 3741:2010

Foreword
Introduction
1 Scope
2 Normative references
3 Terms and definitions
4 Reference meteorological conditions
5 Reverberation test room
6 Instrumentation and measurement equipment
7 Definition, location, installation, and operation of
   noise source under test
8 Measurements in the reverberation test room
9 Determination of sound power levels and sound energy levels
10 Measurement uncertainty
11 Information to be recorded
12 Test report
Annex A (informative) - Guidelines for the design of
        reverberation test rooms
Annex B (informative) - Guidelines for the design of rotating
        diffusing vanes
Annex C (normative) - Reverberation test room qualification
        procedure for the measurement of broad-band sound
Annex D (normative) - Reverberation test room qualification
        procedure for the measurement of discrete-frequency
        components
Annex E (informative) - Extension of frequency range to
        frequencies below 100 Hz
Annex F (normative) - Calculation of octave band sound
        power levels and sound energy levels, A-weighted
        sound power levels and A-weighted sound energy
        levels from one-third-octave band levels
Annex G (informative) - Guidelines on the development of
        information on measurement uncertainty
Bibliography
Annex ZA (informative) - Relationship between this European
         Standard and the Essential Requirements of EU
         Directive 2006/42/EC

ISO 3741:2010 specifies methods for determining the sound power level or sound energy level of a noise source from sound pressure levels measured in a reverberation test room. The sound power level (or, in the case of noise bursts or transient noise emission, the sound energy level) produced by the noise source, in frequency bands of width one-third-octave, is calculated using those measurements, including corrections to allow for any differences between the meteorological conditions at the time and place of the test and those corresponding to a reference characteristic impedance. Measurement and calculation procedures are given for both a direct method and a comparison method of determining the sound power level and the sound energy level.In general, the frequency range of interest includes the one-third-octave bands with mid-band frequencies from 100 Hz to 10 000 Hz. Guidelines for the application of the specified methods over an extended frequency range in respect to lower frequencies are given in an annex. ISO 3741:2010 is not applicable to frequency ranges above the 10 000 Hz one-third-octave band.The methods specified in ISO 3741:2010 are suitable for all types of noise (steady, non-steady, fluctuating, isolated bursts of sound energy, etc.) defined in ISO 12001.The noise source under test can be a device, machine, component or sub-assembly. ISO 3741:2010 is applicable to noise sources with a volume not greater than 2 % of the volume of the reverberation test room. For a source with a volume greater than 2 % of the volume of the test room, it is possible that the achievement of results as defined in ISO 12001:1996, accuracy grade 1 (precision grade) is not feasible.The test rooms that are applicable for measurements made in accordance with ISO 3741:2010 are reverberation test rooms meeting specified requirements.Information is given on the uncertainty of the sound power levels and sound energy levels determined in accordance with ISO 3741:2010, for measurements made in limited bands of frequency and for A-weighted frequency calculations from them. The uncertainty conforms to ISO 12001:1996, accuracy grade 1 (precision grade).