| 摘要 |
<p>The cellular telephone (100) is provided with the capability for automatically adjusting the gain of a microphone (102) 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 users to speak more loudly in noisy environments. Also, by decreasing the microphone gain, any clipping that might otherwise occur as a result to the user speaking more loudly is avoided and the signal to noise ratio is not thereby decreased. Furthermore, because the microphone gain decreases, the volume level of the voice of the user as it is output from the other party's telephone is not unduly loud. Hence, the other party need not manually decrease the speaker gain of his or her telephone. 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 and microphone gain levels. Also, in the exemplary embodiment, the mobile telephone includes a speaker (104) and the gain of the speaker is adjusted to increase in response to an increase in the background noise level.</p> |
