The Research On Sound Transmission Loss Measuring System Of Acoustic Material

The acoustic material is an effective measure which could reduce noise and improve acoustic environment. So, it is important to do research on the acoustic material. One of important factors in evaluating the performance of the acoustic material is the sound transmission loss. The more the sound transmission loss is, the better the performance of the acoustic material is. There are two ways to measure the sound transmission loss. One is the reverberation chamber way which is one of standards in China, the other is impedance tube way. The reverberation chamber way isn't suitable to use in lab. In this paper, there are three points: principle and computing of measuring sound transmission loss, developing the sound transmission loss measuring system and digital design of sound transmission loss measuring system.First of all, principle and computing of measuring sound transmission loss.First, this paper introduces basic knowledge about acoustics and acoustic measuring. Then this paper introduces the principle and requirements of reverberation chamber, and gets the formula from this system. At last, according to three-microphone method, four-microphone with two different ends method and four-microphone method, this paper compare with this three methos from principle, formula and measuring ways.Second, developing the sound transmission loss measuring system. This paper develops sound transmission loss based on Pulse system according to four-microphone method. And this paper introduces impedance tube, speaker, amplifier and Pulse system from technical parameter, choosing principle, sets out the measuring steps and some details which need to be paid attention to. And test the sound transmission sound of rubber and acoustic crystal using this measuring system. At last, develop two caculating softwares using Matlab and VC, which can get the sound transmission loss of acoustic material according to the data which be got from the sound transmission loss measuring system.Third, digital design of sound transmission loss measuring system. This paper designs the sound transmission loss processing equipment based on DSP and caculates the sound pressure and phase by DSP program. The result is equal to the data which be got from measuring system based on Pulse system. It proves that this design and program is available.