| 摘要 |
PURPOSE:To prevent deterioration in an audible function caused by noise and a shock sound of an instantaneously high sound pressure level by outputting the sound as the adjustment sound after a signal level of a signal component of an external sound exceeding prescribed sound pressure level is reduced among output signals from a microphone. CONSTITUTION:When an amplifier means 13 reduces a signal level of a signal component of an external sound exceeding a prescribed sound pressure level included in a sound collection signal S2 and outputs the resulting sound, the external sound is outputted as an adjustment sound with a low sound pressure level and the deterioration in the audible sense function due to noise is prevented. Furthermore, when a sound collection signal S1 is received continuously with a higher signal level than that of a normal conversation sound to the device, a control means 12 allows 1st and 2nd filter circuits 11, 14 to change their cut-off frequency toward higher and lower frequencies respectively in matching with the level of the sound collection signal and allows a signal level attenuation means 15 to increase the attenuation rate in matching with the level of the collection sound signal S1. An external sound under noise is sounded at a low sound pressure level in an intermediate frequency band. |
