Research On Measurement Of Room Impulse Response Based On Image Source Method

Acquiring the room impulse response, the important estimation parameter of acoustical field, such as including echo number, echo distribution, reverberation time can be obtained.The accurate measurement of room impulse response is the key of room sound field simulation technology. Its accuracy affects directly the design effect. Among the methods of room impulse response measurement, the image source method, as a classical computer simulation method, has the advantages of high precision, wide application range, low cost. It has been applied in many fields including acoustical field, noise control,and virtual reality. In this paper, the sound pressure and energy impulse response measurements based on image source method are studied deeply. And the energy decay curve and room reverberation time estimation problem are discussed through the room impulse response.After introducing the definition of room impulse response, the various measurement method of room impulse response, firstly, the basic principle of image source method is stated systematically, the improved algorithm based on the transformation to the frequency domain and negative reflection coefficient is analyzed. Then, taking a rectangular laboratory as example, the pressure room impulse response is measured practically by using precision acoustic instrument and the result is compared with that of original image source method and the improved algorithm respectively. It is shown that the improved algorithm is more accuracy and reliability. After that, energy impulse response is simulated by image source method and acoustic energy propagation law. And the effect of signal frequency on the method is discussed.The energy decay curve and room reverberation time are estimated by room pressure impulse response and energy impulse response, separately. Finally, after measuring the reverberation time of our laboratory, the comparison and analysis with Sabine algorithm, Erying algorithm and Impulse response algorithm is made. The experimental results show that reverberation time estimate method of using energy impulse response obtaining energy decay curve has the higher accuracy and reliability.