TESTING SOUND INTENSITY PROBES IN INTERFERENCE FIELDS

This paper examines and discusses some of the problems in testing the performance of sound intensity measurement systems in interference fie lds. A plane standing wave field with a known standing wave ratio of a n appropriate size is shown to be suitable for revealing various techn ical deficiencies, for instance phase mismatch or a finite relative se nsitivity of the microphone vents. Various arrangements for generating such a field have been examined. It is concluded that a standing wave tube of an appropriate width and terminated either passively or activ ely is suitable for testing intensity measurement systems at low frequ encies, whereas free-field methods are not. No suitable arrangement fo r testing at high frequencies has been found.