Optimization on constrained single-layer absorbers by simulated annealing

As the thickness of sound absorber is often confined by the necessity of worker's maintenance and access in the practical engineering work, the consideration of maximal sound absorption on the sound absorber with limited thickness becomes important and essential. In this paper, by using the simulated annealing (SA), a stochastic relaxation technique based on the analogy of the physical process of annealing metal, a single-layer absorber, including (1) one layer of perforated plate; (2) one layer of acoustic fiber; (3) one layer of air space; and (4) a rigid-backing wall, is optimized under the thickness constraints. A numerical case in dealing with pure tone noise of 350 Hz was exemplified. Before optimization, a sample was tested and compared with the experimental data for accuracy check of mathematical model. Results proved that SA optimization provides a quick and efficient approach on the design of single-layer sound absorbers under fixed thickness.