Editing PSOLA

[[File:Analiza cech suprasegmentalnych języka polskiego Fig.7.1 (p.63).jpg|thumb|300px|Oscillograms, spectrograms and intonograms of Polish expression (a) ''"jajem"'' [egg] (b) ''"ja jem"'' [I'm eating] (c) ''"nawóz"'' [fertiliser] (d) ''"na wóz"'' [on a cart]<ref>{{cite thesis | type=Ph.D. thesis | url=https://commons.wikimedia.org/wiki/File:Analiza_cech_suprasegmentalnych_j%C4%99zyka_polskiego_na_potrzeby_technologii_mowy.pdf | author=Grazyna Demenko | title=Analiza cech suprasegmentalnych jezyka polskiego na potrzeby technologii mowy | institution=Uniwersytet Im. Adama Mickiewicza W Poznaniu | series=Seria Jezykoznawstwo Stosowane | volume=17 | year=1999 }} Fig.7.1, p.63.</ref>]]
'''PSOLA'''  (Pitch Synchronous Overlap and Add) is a digital [[signal processing]] technique used for [[speech processing]] and more specifically [[speech synthesis]]. It can be used to modify the [[pitch (music)|pitch]] and [[duration (music)|duration]] of a speech signal. It was invented around 1986.<ref>{{cite book |doi=10.1109/ICASSP.1986.1168657|chapter=Diphone synthesis using an overlap-add technique for speech waveforms concatenation|title=ICASSP '86. IEEE International Conference on Acoustics, Speech, and Signal Processing|volume=11|pages=2015–2018|year=1986|last1=Charpentier|first1=F.|last2=Stella|first2=M.|s2cid=62440369}}</ref>

PSOLA works by dividing the speech waveform in small overlapping segments. To change the pitch of the signal, the segments are moved further apart (to decrease the pitch) or closer together (to increase the pitch). To change the duration of the signal, the segments are then repeated multiple times (to increase the duration) or some are eliminated (to decrease the duration). The segments are then combined using the [[overlap add]] technique.

PSOLA can be used to change the [[Prosody (linguistics)|prosody]] of a speech signal.

==See also==
* [[Audio time stretching and pitch scaling]]

==References==
{{Reflist}}

==External links==
*[https://web.archive.org/web/20120217003930/http://cnx.org/content/m12474/latest/ Changing Pitch with PSOLA for Voice Conversion] (Archived from [http://cnx.org/content/m12474/latest/ the original])
*[http://research.spa.aalto.fi/publications/theses/lemmetty_mst/thesis.pdf A thesis that discusses PSOLA with diagrams] (PDF format; see page 35, which is page 44 of the PDF) [https://web.archive.org/web/20220309003723/http://research.spa.aalto.fi/publications/theses/lemmetty_mst/thesis.pdf (Archived)]

{{Speech synthesis}}

[[Category:Speech synthesis]]


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