1997-05-20

Verification of a Miniature Reverberation Room for Sound Absorption Measurements Using Corner Microphone Technique 971895

The paper reports the results of sound absorption verification studies of a rectangular parallelepiped reverberation room that is a dimensionally scaled (miniature) version of a full-size, reference reverberation room. The qualification procedure compares the measurement results obtained in the miniature (mini-verb) room with that determined for the same sample in the reference room, where traditional pressure microphone techniques and decay measurements are employed.The absorption measurements in the mini-verb room, however, are based upon a new technique which relies upon the use of boundary microphones installed in very close proximity to each intersection of three room boundaries (i.e., the eight (8) trihedral corners). An array of boundary microphones, one in each corner, is used in place of a traditional spaced array of pressure microphones, or of a single moving microphone.The results of this work demonstrate that the corner microphone technique allows sound absorption measurements within the mini-verb room to compare favorably to results in the reference room, while also allowing several advantages over traditional microphone approaches. Verification studies show that the measurement uncertainty of absorption data is influenced by the number of stationary sound diffusers within the mini-verb room, and that the number and locations of these diffusers strongly influences the degree to which mini-verb room absorption results agree with results in the reference room.

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