US Patent 7734265 Audio muting circuit and audio muting method

In an audio muting circuit, after a short delay from a first time at which a first mute signal generation circuit causes a first mute signal to fall from “H” level to “L” level, a second mute signal generation circuit causes a second mute signal to fall from “H” level to “L” level at a second time. A third mute signal generated by combining the first and second mute signals is caused to fall from “H” level to a predetermined level at the first time, and caused to fall from the predetermined level to “L” level at the second time. Thus, at the start of muting, the level of an audio signal is increased in stepwise manner. In this way, noise generated at the start of muting can be reduced.