[mgeorgoulo]

Very good results and embarrassingly easy to implement!

The very stretched waveform did contain some audible artifacts, but I think other methods like FFT would introduce some as well.

This kind of trick works because our hearing is frequency-based. So the crucial thing is to preserve the frequencies and it is going to sound exactly the same.

Spatial mapping of frequencies in the human ear here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2394499/ (see fig 5.)

Trying this with an image for example wouldn't work, because our vision is sample-based. Imagine splitting an image in tiny fragments and repeating/interpolating them on top of one another.