| 摘要 |
PROBLEM TO BE SOLVED: To allow the ease of listening to a telephone call voice with less throughput. SOLUTION: An environmental ambient noise level included in an input audio signal from a microphone 22 is extracted by a low pass filter 33. An output signal of the low pass filter 33 is subjected to envelope detection by an envelope detector 44, and the detection signal is used as a control signal of an automatic level controller 49. A reception voice signal is supplied to the automatic level controller 49. Input/output characteristics of the automatic level controller 49 are controlled by the control signal generated from the environmental ambient noise level. Concretely, input/output characteristics of the automatic level controller 49 are so controlled that an output level is higher with respect to an input level when the environmental ambient noise is large. COPYRIGHT: (C)2009,JPO&INPIT
|
