ASA 125th Meeting Ottawa 1993 May

1pEA6. Field calibration and check-out of an intensity measurement system using a simplified probe and a reference sound source.

Angelo J. Campanella

Campanella Associates & ACCULAB, 3201 Ridgewood, Dr., Columbus, OH 43026

There is need for a simple field check-out and calibration method for intensity measurement systems. Microphones, preamps, accompanying software, and data display constants can come in question after shipping, reassembly, and resetting. A simplified and standard method of exercising the total measurement system in a few minutes from microphone to display is presented. Microphones are mounted in the side-by-side configuration described by Per Bruel [2nd ICA (Sept. 1985)]. The sound field around an ACCULAB RSS-101 [Inter-Noise 91, 961--964] reference sound source (RSS) is sweep-surveyed [Tachibana, Inter-Noise 91, 1041--1044] over the five sides of an enclosing 1-m cube. This intensity survey method tends to cancel external noise and reflections in a wide variety of environments (shops, offices, outdoors, etc.). Instrument software is then set to display sound power in octave bands that can be directly compared with the laboratory calibration values known for the RSS-101. Sound power agreement within 1 to 2 dB will be found A-weighted and in the 250-Hz to 2-kHz octave bands with a nominal 1-in. (25-mm) microphone spacing. System performance in lower and higher frequency bands may be verified by repeating the test with appropriate microphone spacing.