PURPOSE: To optionally select all musical intervals in a wider musical interval range by determining oscillation frequency and a frequency division ratio by a ROM.

CONSTITUTION: The musical interval generating circuit is constituted of a NAND circuit 2, a plurality of inverters 3, 4, a resistor 1, a plurality of capacitors 5 to 16, a CR oscillation circuit consisting of a plurality of switches 17 to 28, a frequency dividing flip flop circuit 33, a plurality of programmable counters 30 to 32, a 1st decoder 36 for controlling the switches 17 to 28, a 2nd decoder 34 for controlling the counters 30 to 32, and a ROM 35 for determining the inputs of the decoders 34, 36. One of the capacitors 5 to 16 is selected by a signal read out from the ROM 35 to determine the oscillation frequency of the CR oscillation circuit, the frequency division ratio of the counters 30 to 32 is determined similarly by a signal read out from the ROM 35 and an optional sound interval can be generated from the combination of the oscillation frequency and the frequency division ratio.