| 摘要 |
The mobile telephone (100) is provided with the capability for automatically adjusting the gain of a microphone (102) of the telephone (100) based upon the detected noise level in which the cellular telephone (100) is operated. As the noise level increases, the gain of the microphone (102) is automatically decreased, thereby compensating for the natural tendency of telephone (100) users to speak more loudly in noisy environments. In the exemplary embodiment, the cellular telephone (100) includes a digital signal processor (110) configured or programmed to apply the detected noise level to look-up tables (116, 118) relating various noise levels to appropriate speaker (104) and microphone (102) gain levels. Also, in the exemplary embodiment, the mobile telephone (100) includes a speaker (104) and the gain of the speaker (104) is adjusted to incrase in response to an increase in the background noise level. A method of automatically adjusting the gain of speaker (104) in a wireless communications device (100) includes the steps of obtaining a digital value representing the available headroom, estimating the background noise level, and adjusting the volume based on the background noise estimate and the available headroom. Thus, for example, the need for manual volume control buttons on a cellular telephone (100) is eliminated.
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