Modeling of acoustic noise attenuation by the use of composites

The mechanism that causes noise reduction by means of composites is found to be conversion of acoustic to thermal energy as sound waves reverberate against walls of tiny voids in the composite materials. Experimental work is reviewed, and acoustic transmission functions are posed. Transmission loss is described using electrical analogies and classical wave theory. State variable and computer-aided design models that will analyze and predict the noise environment are described. The state variable model is appropriate if the number of state variables can be reduced and if the interdependence of state derivatives with state and control variables can be ascertained. The attenuation process is found to be composite-material-dependent and composite-dimension-dependent