| 摘要 |
The present invention relates to an apparatus and a method for volume control in digital telephones such as second generation mobile telephone terminals, third generation IMT 2000 image mobile telephone terminals, and ISDN (integrated service digital network) terminals. In particular, an apparatus and a method in accordance with an embodiment of the present invention measure background noise and adjust volume of received sound and/or ring signal accordingly. An embodiment of the present invention measures background noise before ringing ring signal and adjusts volume of ring signal. While communicating, the apparatus automatically adjusts volume of received sound in response to the measured background noise. A telephone terminal in accordance with an embodiment of the present invention includes voice/non-voice determination part, volume measurement part, and gain control part. The voice/non-voice determination part separates pure background noise from composite signal (voice+background noise). The volume measurement part measures amplitude of the background noise. The gain control part adjusts volume of received sound in response to the measured results. Signal processing is performed in digital domain and DSP is employed. Consequently, the digital telephone in accordance with an embodiment of the present invention is able to prevent noise pollution usually caused by loud ring signal and provide optimized volume for telephone users.
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