unnaturalness of a sound quality variation before and after the silence state as well as the effect of reducing noise in the silence state this second embodiment fades in or fades out namely gradually varies the effect amount of the sound effect not the volume level as in the conventional circuit fig6 shows the configuration of a sound effect circuit according to a third embodiment of the present invention the sound effect circuit denoted by reference numeral 1 includes a sound effect amount controller 7 a 16 bit sound effect unit 3 an auto level controller alc 14 a programmable gain amplifier pga 15 and an over gain determiner 16 the 16 bit sound effect unit 3 and sound effect amount controller 7 have the same functions as those in the second embodiment the auto level controller 14 functions to output an input audio signal directly as an output audio signal the auto level controller 14 also functions to generate a gain control signal based on the signal level of the input audio signal and supply it to the programmable gain amplifier 15 so as to maintain the volume level range of the audio signal to be constant the programmable gain amplifier 15 varies an amplification factor thereof in response to the gain control signal supplied from the auto level controller 14 amplifies the input audio signal by the varied amplification factor and outputs the amplified audio signal as the output audio signal that is when the volume level of the audio signal becomes so low that the.