A study on the standard for sound intensity measurement

Abstract

A study on a traceability system for sound intensity standards required for accurate sound intensity measurements is described in detail. Required characteristics for the system, such as a calibration method for sound intensity meters involving a field calibrator and a working standard, are discussed. A free‐field calibration method using a progressive wave or a standing wave in an anechoic room is proposed. This is valid for the estimation of accuracies of intensity measurements in complicated actual sound fields. Some ideas on the generation of a calibrating sound field and a standard sound intensity probe are given. The standard probe is composed of several pressure microphones mounted on a rigid sphere and is precisely calibrated using a laboratory standard condenser microphone. To obtain enough accuracy in intensity measurements using the system, five sound intensity meters on the market were tested in various sound fields. The results show that the proposed traceability system is valid for sound intensity measurements.