3pEA2. Accuracy in sound power level determination by the scanning intensity method.

Session: Wednesday Afternoon, December 4

Time: 2:15


Author: Hiroo Yano
Location: Chiba Inst. of Technol., Tsudanuma 2-17-1, Narashino, 275 Japan
Author: Masaru Koyasu
Location: Chiba Inst. of Technol., Tsudanuma 2-17-1, Narashino, 275 Japan
Author: Hideki Tachibana
Location: Univ. of Tokyo, Roppongi, Minato-ku, Tokyo, 106 Japan

Abstract:

The method of determining sound power levels of noise sources by the sound intensity technique has been specified in ISO 9614 Part 1 (precision, engineering, and survey grades by the discrete point method) and Part 2 (engineering and survey grades by the scanning method). In addition to these, the work of drafting, Part 3 (precision grade by the scanning method) has just started in ISO/TC43/SC1/WG25. In order to obtain data for the specification of the measurement accuracy of the scanning intensity method, a basic experimental study has been done. In this study, an artificial sound source (a loudspeaker array) with complicated sound radiation characteristics and two actual sound sources (a vacuum cleaner and a compressor) were used as the sound sources under test. The sound power level of each sound source was determined in each 1/3 oct band from 50 Hz to 6.3 kHz and those in the octave band and A-weighted values were calculated from the values in the 1/3 oct bands. From these results, the measurement repeatability, the influences of the field nonuniformity, and the temporal variability on the measurement accuracy, and the field indicators were investigated.


ASA 132nd meeting - Hawaii, December 1996