Measurement of short duration high level impact noises

Abstract

Over the past few years there has been a growing suspicion that in shipyards, and in metal working industries with punch presses and forging processes, etc., the acoustic environment contains very short duration high level impulses. Since impulsive sounds as a rule are of very short duration, the human ear, and the standardized sound level meter can far from measure correctly the maximum sound pressures of impulses, simply because the integration time of the human ear and of the sound level meter is considerably longer than the impulse duration. Furthermore, the relatively long time intervals between short impulses, make the use of a sound level meter with “peak” holding capacity difficult in practice. In this article it is shown how the peak pressures can be measured three times a second and Leq every minute with the aid of two sound level meters (one with 30‐μs rise time and the other an integrating sound level meter) and a two channel level recorder. The instrumentation setup is battery driven and can operate without attention for seven days. The acoustic environments of a number of different industries have been measured with this set of instruments. The results show that in metal industries the levels of the short duration impulses are considerably higher than those found in wood industries.