Improve Sound Absorption Coefficient Test System Of Reverberation Chamber Method

A variety of sound-absorbing materials and sound absorption structure are widely used in hall sound quality design,noise control and acoustic environment control,the sound absorption coefficient is an important parameter in the selection of sound-absorbing material and sound absorption structure.The measurement of sound absorption coefficient mainly includes impedance tube method and reverberation chamber method.The reverberation chamber method measures the random incident sound absorption coefficient of the sound absorbing material,which conforms to the actual working condition and is widely used.This thesis has a certain practical value in improving the sound absorption coefficient test system of reverberation chamber.In this paper,we first aim at the problem that intermittent sound source method narrow band as the excitation source test process cumbersome,data processing time-consuming,using broadband noise white noise as the excitation source and programming for data processing which has the function of filtering,converting to sound pressure level,interception T20,least squares fitting to calculate reverberation time,calculate sound absorption coefficient and other functions.Secondly,the impulse response integral method includes the balloon blasting and MLS are realized.The data processing program has the function of calculating the impulse response,filtering the impulse response,converting it into the sound pressure and integrating it in the back of the square,converting it into the sound pressure level,cutting the decay curve and fitting,calculating the reverberation time,calculating the sound absorption coefficient,etc.Finally,the improved interruption sound source method and the impulse response integral method are used to measure the sound absorption coefficient of the representative sound absorbing material in the reverberation chamber,verify the accuracy of the improved test method,and make the data processing operation interface.The conclusions are as follows: Improved intermittent sound source test system than the previous use of narrowband sound source excitation signal measurement material sound absorption coefficient test efficiency increased by 18 times.The method of impulse response integral balloon blasting and MLS material sound absorption coefficient test method and data processing function are realized.Using the improved method and the impulse response integral method to measure the sound absorption coefficient of the porous absorbent material polyester fiber cotton and the resonant sound absorption structure perforated aluminum plate,The results show that the two test methods are accurate.The interrupt source method graphical user interface compiled into executable program,running well.