Measurement of the sound transmission loss of circular and slit-shaped apertures in rigid walls of finite thickness by intensimetry

A series of experiments was conducted to determine the transmission loss of circular and slit-shaped apertures. An effective measurement method, sound intensimetry, was employed in the investigation. The measured transmission loss was in very 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.