| 摘要 |
PROBLEM TO BE SOLVED: To provide a sounder that does not reacts to a sudden noise but quickly responds to the overall change in a surrounding noise so as to adjust tone quality and a tone volume of a reproduced tone depending on the characteristics of the surrounding noise. SOLUTION: The sounder is provided with a noise level detection means 111 that detects a surrounding noise level, a minimum level detection means 112 that detects a minimum noise level, and a tone quality tone volume adjustment means 108 that controls the tone quality and the tone volume of the reproduced tone in response to the minimum noise level obtained by the minimum level detection means, and does not detect a noise with a large level caused suddenly but quickly detects a noise changed totally by detecting a minimum noise level changing every moment.
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