PURPOSE: To expand sound signals, where the time base is compressed by a tape recorder, to sound signals having the same pitch as original sound, by controlling the read and the write of sound reproducing signals onto a memory element by clocks of the frequency according to recording and reproducing speed rates.

CONSTITUTION: Sound signals recorded on a tape recorder in recording speed v0 are reproduced in reproducing speed v=nv0 and have the time base compressed. These compressed signals are wrtten in BBD-A through switch S4, which is switched by the gate signal outputted from switch control circuit 70, by clocks of frequency nf0 generated by frequency converter circuit 60, where reproducing speed signals are applied, and are read out by clocks of frequency f0 generated by oscillator circuit 50, and expanded reproducing sound has the same pitch as the original sound. The write and read speed is controlled similarly for other BBD-B and BBD- C parallel with BBD-A, and the pitch of the compressed and expanded reproducing sound can be made equal to the pitch of the original sound.