| 摘要 |
The device includes noise detector(20), amplifying circuit(22), rectifying circuit(24), integral circuit(26), mode setting system(36), voltage amplifier(50) according to the mode, output amplifier(60), output level setting mode(30) and comparator(28). The noise detector means includes microphone(120) to collect noise around the listener. If the user is in a loud noise circumstance, the volume is up automatically; and when the noise is down, the volume is down successively.
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