| 摘要 |
In so-called Code Excited Linear Prediction (CELP) coding methods for speech signal transmission, a codebook look-up method is used which is very processor-intensive. To conserve power, during speech pauses not only the transmitter but also the speech coder is turned off substantially completely. Consequently, when the speech signal resumes there is a transition interval before the filters of the speech coder become adjusted to full operation. For this reason, according to the invention, the filters are not turned off during speech pauses but are directly driven by codebook excitation vectors which correspond to the speech signal then being processed. As a result, there is a smoother and hardly perceptible transition between background noise and the speech signal when the latter resumes. An artificial background noise is produced in the receiver during speech pauses.
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