Fourier analysis tells us that you can do a darn good job modeling any periodic waveform by adding together a series of sine waves. The image below was lifted from the Wikipedia article on the Gibbs phenomenon, in which the goal is to assemble a square wave.
On Jim Bumgardner’s KrazyDad blog I came across this talking piano. It’s from a German-language documentary, but the modeled words are in English. What’s going on? In a process similar to Fourier analysis, you can play lots of piano notes that together add up to a pretty good approximation of someone talking. Spoken words have lots of structure, and musical notes are building blocks of acoustic structure. With the help of a computer and many-fingered robotic pianist, you can make a piano talk.
It’s an uncanny sound. I think it’s just begging to appear in a haunted house movie.