Audio pitch shifting with Fourier transform

John F. McGowan on Math-blog.com has an interesting article on audio pitch shifting by manipulating the Fourier transform of the voice and some additional mathematical acrobatics. This produced a recognizable pitch shifted voice and a relatively smooth pitch shifted voice similar to the output of the analog processing.

Traditional pitch shifting algorithms give artificial qualities to the pitch-shifted voice. The improved algorithms can create more natural sounding pitch-shifted voices. These voices can be used for humor, entertainment, or emphasis in movies, television, video games, video advertisements for small businesses, personal and home video, and in many other applications.

This video is President Obama’s original introduction from his April 2, 2011 speech on the energy crisis.

This video is President Obama speaking with his pitch doubled by shifting the Fourier components but without the mathematical acrobatics to compensate for un-centered frequency components:

This video is President Obama speaking with a chipmunked voice; his pitch has been doubled.

This video is President Obama speaking with a deep voice; his pitch has been reduced to seventy percent of normal.

This video is President Obama speaking with a voice similar to the voice of Mickey Mouse:

© 2011 John F. McGowan, Source : math-blog.com

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