| 摘要 |
<p>Handsfree telephony continues to be an increasingly desirable feature of modern telecommunications, whether in a conference room or mobile setting. Fundamental to the user acceptability of these systems is the performance of algorithms for acoustic echo cancellation, the purpose of which are to prevent the far-end signal from being transmitted back to the far-end talker. Most speech coding algorithms are based on some variant of Linear Predictive Coding (LPC), which reduces the amount of bits sent across a channel. Instead of doing echo cancellation in the time domain, the invention involves operating an acoustic echo canceller on the LPC parameters at the receiver, before the decoding stage. Data which has undergone this transformation is in a form more amenable to echo cancellation. Specifically, the removal of signal correlation through the LPC process improves the convergence properties of adaptive filters using simple adaptation algorithms such as the Least Mean Square (LMS) algorithm. In addition, the echo cancellation process and coding process can share some of the computation processing load since the domain transformation is already part of the coding stage. <IMAGE></p> |
