| 摘要 |
A dynamic filter (20) uses a minimum level of an envelope signal to indicate the noise level of the environment. The noise level prefereably corresponds to blank spaces in the voice signal. This minimum level noise signal provides a simple dynamic indication of the noise. The noise level is used by threshold level generator (46) to set a threshold level, The threshold level and an envelope signal is used by an expander (48) to determine an attenuation value for an input signal. In the preferred embodiment, multiple frequency bands (32, 34) are individually processed.
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