PURPOSE: To obtain a reverberation sound approximate to an actual sound field and having the directivity, by connecting the output terminal of a signal delay element to the input side of another channel as well as to an original signal circuit of each channel.

CONSTITUTION: The signal applied to an R input receives a time delay from a signal delay element DER and is then mixed with an R original signal with a proper ratio through an adding amplifier A.A to be turned into an R output. At the same time, the signal is attenuated by an attenuator ATT.L that varies the degree of coupled transmission between the delay elements DER and DEL, mixed with an L input, receives a delay from the element DEL and is mixed with an L original signal to be turned into a part of an L output.