PURPOSE: To reduce the noise without damaging the dynamic range of the audio signal high band, by providing a high band attenuating means whose frequency characteristics are so changed that the attenuation quantity of the high band components becomes larger when a drop-out or the like of a reproduced RF signal is generated.

CONSTITUTION: In a deemphasis circuit 15, for example, an FET is used as a variable resistance circuit 17, and the resistance value is so changed that the time constant of this circuit 17 and a capacitor C1 is approximately equal to a time constant γ0 of an emphasis circuit for the absence of a noise detection signal and becomes γ1 larger than the time constant γ0 for the presence of the noise detection signal. That is, when the noise detection signal exists, the gain of the circuit 15 is lowered in a high band higher than a roll-off frequency f1=1/2πγ1, and the attenuation quantity of high band components becomes larger than an existing audio signal. Consequently, even if noise components exist in the input, the output has noise components reduced by a considerable quantity, and a high reproducibility is attained.