Common-Pole Analysis and Application to Acoustic Echo Cancellation

• Main Authors: Jing-Shan Liang, 梁菁珊
• Other Authors: Wen-Whei Chang
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/12571203228334276559

碩士 === 國立交通大學 === 電信工程系 === 88 === In many hand-free applications, it is necessary to reduce the acoustic echo incurred by the coupling between the loudspeaker and the microphone. In this thesis, we used an IIR adaptive filter to simulate the room impulse response, which describes the sound transmission characters between a source and a receiver in a room. The simulation of the time-varying room impulse response is formulated as a system identification problem that is amenable to the application of normalized least-mean-square algorithms. The study of sound wave transmission reveals that all possible echo paths in the same enclosure room are characterized by common poles, each of which corresponds to the resonance frequency (eigenfrequency) of one room transfer function. Proceeding in this way, only the zeros of an IIR echo canceller need to be updated. Furthermore, the common poles can characterize part of the echo path and hence it offers a better choice for initial parameter setting of the IIR filter. Simulation results indicate that the proposed echo canceller with common poles not only reduces the computational complexity but also results in more echo cancellation compared with other IIR cancellers.