Editing Phase vocoder (section)

{{Short description|Vocoder algorithm}}
[[File:GeneralizedPrinciple_TSM.png|thumb|right|450px|Decomposition of an audio signal into frames. Frames are then processed and reassembled.]]
A '''phase vocoder''' is a type of [[vocoder]]-purposed algorithm which can [[Interpolation|interpolate]] information present in the [[frequency]] and [[time domain]]s of audio signals by using [[Phase (waves)|phase]] information extracted from a frequency transform.<ref>{{cite web |last1=Sethares |first1=William |title=A Phase Vocoder in Matlab |url=https://sethares.engr.wisc.edu/vocoders/phasevocoder.html |website=sethares.engr.wisc.edu |access-date=6 December 2020}}</ref>  The computer [[algorithm]] allows [[frequency-domain]] modifications to a digital sound file (typically [[Audio timescale-pitch modification|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 transform]]s. 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 time-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.