| 摘要 |
PURPOSE: A portable wireless telephone device implementing a full duplexer speaker phone is provided to reverse sound signals, causing howling inputted to a microphone by being outputted to a speaker, using a circuit, so as to eliminate a generation cause of howling. CONSTITUTION: A speaker(50) outputs sound signals. A microphone(60) receives the sound signals. A microphone amplifier(80) amplifies the sound of the microphone(60). A sound eliminating circuit(40), combined with the sound signals outputted through the speaker(50), inputs the signals inputted to the microphone(60) to a reverse input of the microphone amplifier(80), to eliminate signals generated by the sound combination in outputs of the microphone amplifier(80).
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