Title: The effects of microphone placement and azimuth on peak sound pressure level of type A impulses
Abstract: Single, repeatable type A impulses were generated by colliding steel spheres in an acoustically reverberant room, and measured as A-weighted sound levels by a sound level meter having four exponential time averaging modes with time constants ranging from 2 μs to 1 s. Measurements using peak hold (2-μs time constant) were then obtained on KEMAR at four azimuths and four microphone placements at each azimuth. Comparative measurements showed peak hold to give the most accurate estimation of A-weighted sound level, as verified electrically. The remaining three underestimated this value. Maximum underestimation of 34.8 dB was demonstrated using the slow time constant. KEMAR measurements demonstrated peak A-weighted sound levels to be sensitive to both microphone placement and azimuth. Measurements made in the reference field and at external microphone placements tended to underestimate peak A-weighted sound level at the tympanic membrane (TM). Two conclusions were reached. Time constant of the exponential time averaging must be shorter than the duration of the signal. Peak A-weighted sound level cannot be predicted by measurements made at sites other than at the plane of the TM.
Publication Year: 1986
Publication Date: 1986-12-01
Language: en
Type: article
Indexed In: ['crossref']
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