Numerical simulation of the laboratory sound insulation determination experiments

摘要

This paper explores numerical simulations for the experimental evaluation of sound reduction index for building partitions in the low frequency range, i.e. the range in which the modeal density is low in typical rooms. which is reviewed first. simulations are based on the wave theoretical model of acoustic cavities, which is reviewed first. The governing (damped) wave equation is solved approximately by the Modal Approach and by the Finite Element Method. Absorption in rooms is modeled by introducing the flow resistivity, related to the reverberation time, which in turn is measured during the experiment. Two models are employed for the partition. In the first the partition is treated as locally reacting with mass impedance. In the second it is treated as a thick, finite plate. The simulation concerns experiments carried out in two different laboratories-one with the sending room having equal dimensions to that of the receiving room, and the other with the sending room and receiving room having considerably different dimensions. The reverberation also differs significantly between experiments. In one case both rooms are heavily damped, whilst in the other they have long reverberatiosn. I both cases the test object isnominally the same-a single leaf gypsum board aprtition. The results of both simulations by numerical techniques are compared with the experimental results. In both cases the frame supporting the tested aprtition has considerable thickness and a position of the test partition in the suporting frame on the evaluationof the reduction index is studied in the simulations. The Finite Element analysis is carried out on a parallel computer -IBM SP2. Remarks concerning the application of computers of this type for the simulations involving steady state analysis in the frequencydomain are given.