| 摘要 |
PROBLEM TO BE SOLVED: To obtain a noise-canceling headphone capable of withstanding over long-time continuous use with a compact and light power supply battery by a power-saving means. SOLUTION: A noise cancellation function is suspended with the provision of a noise level detection means 20 for detecting whether a noise level is a threshold level or higher, when the noise level detected by the noise level detection means 20 is the threshold or lower; or with the provision of a frequency characteristic detection means 21 for detecting noise frequency band, when the detected frequency band is outside a specified band; or with the provision of a signal level detection means for detecting whether tone signal level is higher than and inclusive of the preset threshold, in case that the detected tone signal level is higher than and inclusive of the threshold. The noise cancelation function will resume, when the noise level is higher and inclusive of the threshold, and the frequency band is inside the specified band, and the tone signal level is lower and inclusive of the threshold. COPYRIGHT: (C)2008,JPO&INPIT
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