| 摘要 |
PURPOSE:To remove the masking of a hearing system due to a noise, by increasing a low-pass gain of a reproduced signal for a lower engine speed than a specified value and a medium and high-pass gain of the signal for a higher engine speed than the specified value in a car room sound reproducing divice of an automobile or the like. CONSTITUTION:An output of a tape recorder 1 is divided into low, medium and high pass components by filters 2-4, added by an adder 8 respectively via voltage gain adjusters 5-7 and applied to a speaker from a terminal 9. While if a noise in a car room detected by a microphone 10 increases, a gain of the gain adjuster 5 is increased through a summing amplifier 21. Further switches 25, 27 are turned on till a speed signal from a frequency voltage converter 15 reaches reference voltage 28, and voltage in accordance with a noise level is applied to summing amplifiers 22', 23', if exceeding the reference voltage, switches 24, 26 are turned on to apply the voltage to the adjusters 6, 7 through summing amplifiers 22, 23. In this way, a masking phenomenon of a hearing system due to an engine noise or the like can be automatically removed. |
