| 摘要 |
PROBLEM TO BE SOLVED: To provide a communication device without causing any howling. SOLUTION: When a control part decides that a handset is put off the hook (step S1), a line is closed by controlling a network control part (step S2) and when the control part detects a signal indicating the depression of a sound- volume up key from an input part (step S3), the gain of an amplifier connected to a speaker is increased by 4 dB (step S5). When the sound volume exceeds a 6th level (step S6), the gain of an amplifier connected to a microphone is decreased by 3 dB (step S7). COPYRIGHT: (C)2003,JPO
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