By storing a digital representation of the impulse response of an equivalent filter in a digital memory, a set of musical tones can be generated in which every tone in the set has the same spectral envelope rather than the same waveshape as occurs when the waveshape, itself, is stored digitally. When the impulse response is stored, rather than the waveshape, completely arbitrary attack characteristics can be obtained including inharmonic and noise components. The impulse response that is required to synthesize any existing periodic tone, including the attack portion, can be derived by shifting the original tone one pitch period and subtracting the shifted tone from the original.