| 摘要 |
<p>An earphone device includes an acoustic tube (1) having an outer diameter nearly the same as the external auditory meatus, one end thereof serving as an auricle-fitting portion (4) and the other end thereof serving as a sound non-reflection end. Vibration plates of an earphone unit (3) and of an internal microphone unit (6) are mounted close to each other on the peripheral surface of the acoustic tube, and they face the inside of the tube. The phase of external noise in the acoustic tube collected by the internal microphone unit is inverted and the phase-inverted sound is produced by the earphone unit, in order to effectively decrease the external noise without oppressing the temple or giving uncomfortable feeling such as sense of oppression even when used for extended periods of time. In the earphone device, furthermore, an external microphone unit (37) is disposed outside the acoustic tube (31), and mixing means (38) is provided to freely change the relative intensity of a signal obtained from the external microphone unit, a feedback signal of an input acoustic signal, and a signal of the internal microphone unit (36). This enables hearing the external sound without the need of removing the earphone device from the ear, and/or listening to the reproduced sound while reducing external noise.</p> |
