The measurement of sound transmission and directivity of holes by an impulse method

Abstract A description is given of an investigation of the transmission of sound through apertures in panels in which short-duration signals are used. The method involves the digital capture of the direct component of the transmitted signal for subsequent FFT analysis. An anechoic condition is thereby simulated which removes source and receiver room effects, which can mask the desired signal when steady state measurement methods are employed. The transmission characteristics of the apertures are thus isolated, and it is seen that measured transmission loss gives promising agreement with prediction obtained with existing approximate theories. The directivity of large circular apertures is investigated and measurement gives agreement with prediction obtained from theory in which a piston-like motion in the plane of an infinite baffle is assumed.