| 摘要 |
PURPOSE:To decrease noises by converting periodic noises to an electric signal and outputting the signal obtd. by inverting the phase of this electric signal and amplifying the signal as a sound. CONSTITUTION:A microphone 21 converts the periodic noises generated by the attachment and detachment of a magnetic tape 3 and a magnetic head 1 to the electric signal. The phase of the electric signal by these noises is inverted in a phase inversion circuit 22. The signal inverted in phase is amplified in an amplifier 23 and a speaker 24 converts this signal to the sound. The sound from the speaker 24, therefore, works to cancel the periodic noises. The periodic noises are attenuated in this way. |
