| 摘要 |
PURPOSE:To enable hearing of sounds which are masked by noises and hard to be heard and to reduce an unpleasant feeling in terms of acoustic sense by adding a signal transmitted through a switch to the signal whose maximum frequency band is delayed so as to output the added signal. CONSTITUTION:A switch 19 is switched to the side of a delay circuit 17 in the normal condition, while a voltage of an output signal eo is turned into a waveform obtained by delaying a voltage of an input signal ei by means of delay circuits 14 and 17. Noises have mainly low frequency components, and a long hours average spectrum is dominated by low band components. As a result, a discrimination circuit 22 will not operate, and the switch 19 is almost switched to the side of the circuit 17. However, a sound has more peak components compared with noises. Accordingly, when the sound is made incident on, a level of a high band signal en exceeds a threshold at a part 24, where the circuit 22 operates, and the switch 19 inverts. Consequently a low band level of the output voltage eo is reduced from an output eld to an output eld' of an arithmetic circuit 18 at the part 24. |
