| 摘要 |
By the speaker detecting device, the test signal is supplied to the output terminal to which the speaker is to be connected. If a speaker is connected to the output terminal, the test sound is output via the speaker. If no speaker is connected to the output terminal, no test sound is output. The test sound detecting unit detects the test sound in the acoustic space and compares the signal level of the test sound with the predetermined threshold level, thereby to judge whether or not a speaker is connected to the output terminal.
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