Identification of Weak Spots in the Sound Insulation of Walls Using a Spherical Microphone Array

摘要

A previously developed spherical microphone array [J. Acoust. Soc. Am., 112(5), 1980-1991rn(2002)] has been used for the identification of localized weak spots in an otherwise highlyinsulatingrnwall (sound transmission class (STC) rating of 56). A sound source and the arrayrnwere placed on opposite sides of a wall sample constructed between two reverberation rooms.rnThe omnidirectional impulse response was measured to each of the 32 array microphones, andrnsubsequent beamforming resulted in 60 directional impulse responses at the array position,rndistributed over all directions. This set of responses was analyzed to identify directions of peakrnsound transmission through the wall. The wall was tested in three configurations: 1. with nornintentional sound leaks (STC 56), 2. with a 5.4 cm diameter hole cut clear through (STC 53), andrn3. with a 3.8 cm diameter sealed-end pipe passed through the 5.4 cm hole (STC 56). The resultsrnobtained with the array approach are compared to a “brute force” scan with a microphone locatedrn0.25 m from the wall. Indications are that the array approach is capable of detecting minorrndefects in the wall.