A PERFORATED PANEL SOUND ABSORBER FOR LOW FREQUENCIES

This paper presented a perforated panel sound absorber with extended tubes from the perforations. The extended tubes made the sound absorption peak move to the low frequency due to the increase of the mass reactance. The theoretical model was also presented to predict the sound absorbing performance. The measurements in the impedance tube gave a good agreement with the predictions. In order to widen the frequency bandwidth of the sound absorption peak multi perforated panel sound absorbers were parallel compounded. The predicting sound absorption coefficient of the compounded sound absorbers also agreed well with the measurements.