| 摘要 |
PURPOSE:To relax constraint for the mounting position, etc., of a microphone or a sounding body, by providing an informing sound cancelling means, and an automatic sensitivity adjuster, cancelling an informing sound from the sounding body inputted from the microphone in a recording time, and varying the sound volume interlocking with the automatic sensitivity adjuster. CONSTITUTION:When the signal of a control signal input terminal 12 is put in a recording state, a variable gain signal generator 5 generates a specific signal shown in figure (a). At such a time, a microphone 3 collects the informing sound, and a signal having a waveform shown in figure (b) appears at the output side of a variable gain amplifier 10. The signal is changed to a signal waveform shown in figure (c), the phase of which is inverted from, and the amplitude of which is equal to the signal waveform in figure (b), and the signal waveform represented in figures (b) and (c) are added at an adder 8, then being cancelled, and the informing sound is not recorded on a magnetic head 11. Meanwhile, an automatic sensitivity adjuster 9 varies the amplification degree of the variable gain amplifier 10 based on the size of a sound signal component, simultaneously, varies the gain of the variable gain signal generator 5. Therefore, the sound volume fitted for a peripheral status can be obtained. |
