| 摘要 |
PROBLEM TO BE SOLVED: To remove noise generated when outputting a signal lower than a prescribed reference level by gradually decreasing the output volume level of a volume control part when it is discriminated the input signal is absent or lower than the reference level. SOLUTION: A 1st comparator part 50 checks the presence/absence of change in the signal inputted from the outside to an input part 10. A 2nd comparator part 60 checks whether a signal level regulated by a gain control part 20 is data normally processable at a signal processing part 30 or not. Based on the output signals from the 1st and 2nd comparator parts 50 and 60, a noise gate 70 controls the gain of the final output. When the signal showing the absence of the input signal or the signal level lower than the reference level is inputted from the 1st comparator part 50 or the 2nd comparator part 60, the value of the output volume from a volume control part 40 is decreased so as to control the gain low. Thus, any noise is not outputted through the output part 80 to the outside. |
