ÖNORM EN ISO 3743-1

1.1 General This patt of ISO 3743 specifies a relatively simple engineering method for determining the Sound power levels of small, movable noise sources. The measurements are carried out when the Source is installed in a hard-walled test room. A comparison method is used to determine to the octave-band Sound power levels of the Source. The spatial average (octave-band) Sound pressure levels produced by the Source under test are compared to the spatial average (octave-band) Sound pressure levels produced by a reference Sound Source of known Sound power output. The differente in Sound pressure levels is equal to the differente in Sound power Ievels if conditions are the same for both sets of measurements. The A-weighted Sound power Ievel is then calculated from the octave-band Sound power Ievels. NOTE 1 Precision methods for the determination of Sound power levels of small noise sources are specified in ISO 3741 and ISO 3745. 1.2 Types of noise The method specified in this part of ISO 3743 is suitable for measurements of all types of noise within a specified frequency range, except intermittent noise consisting of isolated bursts of Sound energy. NOTES 2 A classification of different types of noise is given in ISO 2204. 3 For sources of intermittent noise consisting of shortduration noise bursts, the free-field methods specified in ISO 3744 and ISO 3745 should be used. 1.3 Noise Source The noise Source may be a device, machine, component or sub-assembly. The maximum size of the Source under test depends upon the size of the room used for the acoustical measurements. (See also 4.1). 1.4 Measurement uncertainty Determinations made in accordance with this part of ISO 3743 result, with few exceptions, in Standard deviations of reproducibility of the A-weighted Sound power Ievel equal to or less than 1,5 dß (see table 1). A Single value of the Sound power Ievel of a noise Source d (...abbreviated)