Phase Vocoder

A phase vocoder is a type of vocoder which can scale both the frequency and time domains of audio signals by using phase information. The computer algorithm allows frequency-domain modifications to a digital sound file (typically time expansion/compression and pitch shifting).

At the heart of the phase vocoder is the short-time Fourier transform (STFT), typically coded using fast Fourier transforms. The STFT converts a time domain representation of sound into a time-frequency representation (the "analysis" phase), allowing modifications to the amplitudes or phases of specific frequency components of the sound, before resynthesis of the frequency domain representation into the time domain by the inverse STFT. The time evolution of the resynthesized sound can be changed by means of modifying the time position of the STFT frames prior to the resynthesis operation allowing for time-scale modification of the original sound file.

Read more about Phase VocoderPhase Coherence Problem, History, Use in Music

Other articles related to "phase vocoder, phases":

Phase Vocoder - Use in Music
... British composer Trevor Wishart used phase vocoder analyses and transformations of a human voice as the basis for his composition VOX 5 (part of his larger VOX Cycle) ... Transfigured Wind by American composer Roger Reynolds uses the phase vocoder to perform time-stretching of flute sounds ... Auto-Tune pitch-correcting software, widely used in commercial music production, is based on the phase vocoder principle ...
Audio Timescale-pitch Modification - Phase Vocoder
... signal without affecting the pitch is to build a phase vocoder after Flanagan, Golden, and Portnoff ... samples apply some processing to the Fourier transform magnitudes and phases (like resampling the FFT blocks) and perform an inverse STFT by taking the inverse Fourier ... The phase vocoder handles sinusoid components well, but early implementations introduced considerable smearing on transient ("beat") waveforms at all non-integer ...

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