| 摘要 |
PURPOSE: A speaker phone device of a mobile communication terminal is provided to feed back a level value of a voice output signal outputted from a speaker to a controller, and to compare a level value of a reference voice output signal with the level value of the fed-back voice output signal, in order to increase or decrease an output gain of the speaker, thereby preventing a howling sound. CONSTITUTION: A microphone(100) converts an inputted voice signal into an analog voice signal. A speaker(200) outputs the analog voice signal outside. A CODEC(Coder-Decoder)(300) converts the converted analog voice signal into a digital voice signal, or converts into the analog voice signal to output the received digital voice signal through the speaker(200). A feedback unit(500) feeds back a level value of the analog voice signal outputted to the speaker(200) by being converted from the CODEC(300). A controller(600) inputs the level value of the fed-back analog voice signal, and compares the inputted level value with a level value of a reference analog voice signal, then increases or decreases an output gain of the speaker(200) to equalize the level value of the analog voice signal with the level value of the reference analog voice signal.
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