Indefinite pitch
From Wikipedia, the free encyclopedia.

In music a sound or note of indefinite pitch is one of which it is impossible or relatively difficult to discern the pitch, or rather, the frequency of the fundamental, as opposed to sounds of definite pitch. Sounds with indefinite pitch do not have harmonic spectra or have altered harmonic spectra.

The original article can be found at: http://en.wikipedia.org/wiki/Indefinite_pitch.
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