Average sound level including sonic booms

Abstract

The primary and practical means of monitoring noise in the community or in the factory is to measure the average sound level during a time like an hour, eight hours, or a day. Average sound level is also called equivalent continuous sound level. Sonic booms have been commonly measured and reported in terms of peak wide‐band overpressure, and with less than the 60dB dynamic range needed for A weighting. The present measurements were made directly on more than 16 sonic booms that occurred from airplanes flying the medium‐altitude supersonic corridor northeast of Edwards AFB. The noise measure of a single event particularly useful for calculation of average sound level is the (time integral of A‐weighted squared pressure) sound exposure level. Also measured was the flat (8 Hz–8 kHz) sound exposure level. For aircraft mostly of length on the order of 18 m (59 ft), the peak flat sound pressure level exceeded the flat sound exposure level about 12 dB. The peak flat sound pressure level of 122 dB exceeded the sound exposure level (which possibly included engine noise) by 42 dB, but the difference decreased to 34 dB when the peak pressure level was 135 dB.