ASA 125th Meeting Ottawa 1993 May

1pEA4. Standing wave tube testing of sound intensity probes.

R. W. Guy

Ctr. for Building Studies, Concordia Univ., 1455 de Maisonneuve Blvd., West, Montreal, PQ H3G 1M8, Canada

To ensure correct measurement of sound intensity in highly reactive fields and lower frequencies ((less than or equal to)400 Hz) a standing wave field performance test has been specified in a draft standard (IEC 1043 Instruments for the measurements of sound---instruments which measure intensity with pairs of pressure sensing microphones, Draft Standard 1991). The purpose and requirements of the test are examined from theoretical and experimental perspectives, and suggestions for change are made. It is shown that differing tolerance limits are required if over and underestimate error cases are to be considered. A wider tolerance limit may be specified for the standing wave required by the test and fewer measurements need to be taken (2 in contrast to 15). [Work supported by the National Science and Engineering Research Council Canada---Individual Operating Grant.]