DIN EN ISO 3747:2011-03

This Standard specifies a method for determining the sound power level or sound energy level of a noise source by comparing measured sound pressure levels emitted by a noise source (machinery or equipment) mounted in situ in a reverberant environment, with those from a calibrated reference sound source. 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 octave, is calculated using those measurements. The sound power level or sound energy level with frequency weighting A applied is calculated using the octave-band levels. The method specified in this Standard is suitable for all types of noise (steady, non-steady, fluctuating, isolated bursts of sound energy, etc.) defined in ISO 12001. The method is primarily applicable to sources which emit broad-band noise. It may, however, also be used for sources which emit narrow-band noise or discrete tones, although the measurement reproducibility might then be degraded. The noise source under test may be a device, machine, component or sub-assembly, especially one which is non-movable. The test environment that is applicable for measurements made in accordance with this Standard is a room where the level of background noise is sufficiently low and the sound pressure level at the microphone positions depends mainly on reflections from the room surfaces. Information is given on the uncertainty of the sound power levels and sound energy levels determined in accordance with this Standard, for measurements made in octave bands of frequency and for calculations from those measurements with frequency weighting A applied. The reproducibility conforms with that of either the engineering grade of accuracy (grade 2) or the survey grade of accuracy (grade 3) defined in ISO 12001, depending on the extent to which the requirements concerning the test environment are met.