Determination of Sound Power Level and Systematic Errors. Swedish Council for211 Work Life Research 1997-1612

摘要

Some of the basic international standards for determination of sound power levels211u001econtain known systematic errors which are not dealt with. In particular, the 211u001estandards which base the determination of sound power level on sound pressure 211u001elevel measurements in a more or less free field above a reflecting plane have 211u001ethis weakness. The two errors which are believed to be most important in 211u001epractical applications are the sampling error and the wave front or angle error. 211u001eAt low frequencies and at short measurement distances the near-field error may 211u001ealso become significant. These problems are discussed, theoretial simulations are 211u001ecarried out and measurements on 5 different machines using different methods are 211u001ereported. Improvements are proposed.