| 摘要 |
PURPOSE:To attain ease of listening to an output sound by increasing the output sound of a frequency band causing difficult listening in response to the increase in noise and not increasing too much the entire sound volume. CONSTITUTION:A music signal from a cassette deck 1 and a tuner 2 is selected by a preamplifire 3, divided into three kinds of frequency band signals by a channel divider 4 and inputted to dynamic range controllers 5, 6, 7. A noise signal of a microphone 8 actuates dynamic range controllers 5, 6, 7 via a noise detection circuit 9, a control signal generating circuit 10 and multiplier circuits 11, 12, 13 and as the music signal level is lower, the rising rate of an output acoustic level for a low sound and high sound frequency is increased more. The signal from the dynamic range controllers 5, 6, 7 is outputted from a speaker 17 as a sound via a mixer 14, a variable resistor 15 and a main amplifier 16. |
