Sine-wave speech can be thought of as a sort of auditory illusion, a sensory edge case in which one’s experience has a clear “before” and “after” moment, like going through a one-way door.
Using a copy of [SPICE] a free circuit simulation application, I have created several sine wave sources and summed them together. Seen here, the waves combine into a square wave with it looking ...
The more general form of transferring the frequency domain to the time domain is termed the inverse Fourier transform. See: COMPLEX TONE, FOURIER THEOREM, HARMONIC SERIES, SINE WAVE. Compare: GRANULAR ...