| 摘要 |
The invention relates to an acoustic echo canceller particularly well suited for use in a hands-free terminal or teleconference system. The echo canceller is designed to assess the inherent signal attenuation occurring in the analog loop that connects the terminal to the switch mechanism of the PSTN domain or the PBX domain. The echo canceller is then adjusted in accordance with the degree of signal attenuation manifested by the loop. For high signal attenuation levels, the degree of echo control at the terminal is reduced since the signal attenuation occurring in the loop itself will compensate for the reduction, allowing to reach the echo control target at the far end of the loop (switch side). This feature avoids overly attenuating the echo at the terminal by taking advantage of the inherent echo control provided by the local loop conductors.
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