Experimental study of impulsive sound-level response statistics in a reverberrant enclosure

Abstract

Many industrial noise sources exhibit strong impulse behavior and operate in a reverberant environment. The sound pressure response to this type of source is not adequately described by steady-state formulations when the responses to successive noise impulses are nonoverlapping. An experimental study has been made to assess the influence on the pressure response of such factors as source-receiver location, amount and placement of sound absorbing material, and shielding by barriers. A spark gap serves as a controllable impulsive noise source. The measured responses are the rms sound pressure and its absolute level together with its exceedance probability distribution (EPD). The rms sound pressure relates to the total energy at the receiver while the EPD relates to the time variation of the response sound pressure level. Additionally, the EPD can be used to assess compliance with noise regulations that involve a time exposure. Results of source changes (location, impulse occurrence rate) and enclosure modifications (addition of sound absorbing material or barriers) are presented. [Work supported by NSF Grant GK 4340.]