Investigation of sound absorption performance improvement by perforated plate with background air space

Abstract

The present paper focuses on the effect of tapered orifices and flow on the acoustic absorption performance of perforated plate. We experimentally measured the flow velocity, acoustic pressure, and transfer function using the improved acoustic impedance tube. The normal incidence absorption coefficient was calculated from the measured transfer function using transfer function methods. The peak frequency of the acoustic absorption coefficient depended on the taper angle of the holes of the perforated plate. The peak frequency of the sound absorption coefficient frequency response increases with tapered orifices. Acoustic resistance does not change as the taper angle changes, but acoustic reactance changes as the taper angle increases. The acoustic reactance will be nearly the same whether the orifice tapers upstream or downstream. We discussed the effect of the taper orifices and flow on the specific acoustic performance.