The Study of Two-Stage Acoustic Echo Canceller
碩士 === 國立交通大學 === 電信工程系 === 87 === In this thesis, we present the basic formulations of a two-stage acoustic echo canceller. It offers sufficient echo reduction with less computational complexity. In the proposed system, we use a NLMS FIR filter to cancel the early reflection echo, followed by an ec...
| Main Authors: | , |
|---|---|
| Other Authors: | |
| Format: | Others |
| Language: | zh-TW |
| Published: |
1999
|
| Online Access: | http://ndltd.ncl.edu.tw/handle/13133207956005382841 |
| Summary: | 碩士 === 國立交通大學 === 電信工程系 === 87 === In this thesis, we present the basic formulations of a two-stage acoustic echo canceller. It offers sufficient echo reduction with less computational complexity. In the proposed system, we use a NLMS FIR filter to cancel the early reflection echo, followed by an echo shaping filter to reduce the echo residue. The echo shaping filter can be realized using a time-domain Wiener filter or a frequency-domain generalized spectral subtraction filter. While the time-domain filter is easy to compute, it has some limitations as far as the double talk is concerned. When applying the frequency-domain filter, power spectral densities of echo residue are estimated and then subtracted from the compensation signal. We also explore the benefits of incorporating masking effect of phychoacoustics in the frequency-domain system. Simulations results indicate that the combined use of echo shaping filter and the masking threshold provides an ideal compromise between the echo cancellation and near-end speech quality.
|
|---|