The use of acoustic intensimetry to size air leakage cracks.

Reverberant sound excitation and the sound intensity technique have been used for the measurement of the sound transmission loss of narrow slits in rigid walls. A series of experiments was conducted to determine the transmission loss of slit shaped apertures. The measured transmission loss was in good agreement with existing approximate theories over their accepted ranges of validity. However, the effect of viscosity in small apertures was found to be significant and to vary systematically with the dimensions of the apertures. As predicted by theory, the dimensions of the apertures determine the magnitudes and resonant frequencies of the sound transmission loss curves. It should thus be possible in principle to size air leakage cracks using the technique described in this paper.