Noise Transmission Through Profiled Metal Cladding Part I: Single Skin Measurements

Abstract

The sound reduction of single-skin trapezoidal profiled metal cladding systems often displays pronounced "dips" in mid frequency range. Because of their magnitude and frequency range. these "dips" can be a critical limiting factor in a cladding system's performance towards insulating noise from industrial premises. This paper investigates in detail the sound reduction of these cladding systems. A series of sound reduction measurements employing a systematic and comprehensive change of profile geometry involving 15 cladding systems was conducted to examine the effect of the profile geometry on the sound reduction "dips". It is suggested that the "dips" are caused by resonant vibration modes that are local to the geometry of a profile corrugation. Vibration measurements on cladding sheets excited by a diffuse field in a transmission suite and on free hanging cladding sheets excited by a normal incidence plane wave in an anechoic chamber were conducted to test and confirm the explanation.