Advertisement

How does an audio effects processor perform pitch shifting?

  • T. Dutoit
  • J. Laroche

Abstract

The old-fashioned charm of modified high-pitched voices has recently been revived by the American movie Alvin and the Chipmunks, based on the popular group and animated series of the same name which dates back to the 1950s. These voices were originally performed by recording speech spoken (or sung) slowly (typically at half the normal speed) and then accelerating (“pitching up”) the playback (typically at double the speed, thereby increasing the pitch by one octave). The same effect can now be created digitally and in real time; it is widely used today in computer music.

Keywords

Discrete Fourier Transform Audio Signal Frame Shift Frame Length Hanning Window 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Arfib D, Keiler F, Zölzer U (2002) Time-frequency processing. In: DAFX: Digital Audio Effects. U. Zölzer, Ed. Hoboken (NJ): John Wiley &SonsGoogle Scholar
  2. Bagdasarian R (1958) The Chipmunk song (Christmas don’t be late). Jet Records, UKGoogle Scholar
  3. Dolson M (1986) The phase vocoder: A tutorial. Computer Music Journal, 10(4): 14–27CrossRefGoogle Scholar
  4. Dutoit T (1997) Time-domain algorithms. In: An Introduction to Text-To-Speech Synthesis. Dutoit T. Dordrecht: Kluwer Academic PublishersCrossRefGoogle Scholar
  5. Flanagan L, Golden RM (1966) Phase Vocoder. Bell System Technical Journal, pp 1493–1509 [online] Available: http://www.ee.columbia.edu/~dpwe/e6820/ papers/FlanG66.pdf[07/06/2007]Google Scholar
  6. Laroche J (1998) Time and pitch-scale modification of audio signals. In: Applications of Digital Signal Processing to Audio Signals. M. Kahrs and K. Brandenburg, Eds. Norwell, MA: Kluwer Academic PublishersGoogle Scholar
  7. Laroche J (2003) Frequency-domain techniques for high quality. Voice Modification. In: Proceedings of DAFX-03, 322–328Google Scholar
  8. Laroche J, Dolson M (1999a) Improved Phase Vocoder Time-Scale Modification of Audio. IEEE Transactions on Speech and Audio Processing, 3: 323–332CrossRefGoogle Scholar
  9. Laroche J, Dolson M (1999b) New Phase Vocoder Technique for Pitch-Shifting, Harmonizing and Other Exotic Effects. IEEE Workshop on Applications of Signal Processing to Audio and Acoustics. Mohonk, New Paltz, NY [online]Available: http://www.ee.columbia.edu/~dpwe/papers/LaroD99-pvoc.pdf [07/06/2007]Google Scholar
  10. McAulay R, Quatieri T (1986) Speech analysis/Synthesis based on a sinusoidal representation. IEEE Transactions on Acoustics, Speech, and Signal Processing 34 (4): 744–754CrossRefGoogle Scholar
  11. Puckette MS (1995) Phase-locked Vocoder. Proceedings of the IEEE Conference on Applications of Signal Processing to Audio and Acoustics, MohonkGoogle Scholar
  12. Röbel A (2003) A new approach to transient processing in the phase vocoder. Proceedings of the 6th International. Conference on Digital Audio Effects (DAFx-03), 344–349Google Scholar
  13. Sethares WA (2007) Rhythm and Transforms. London: Springer Verlag [online] Available: http://eceserv0.ece.wisc.edu/~sethares/vocoders/Transforms.pdf [20/3/08]MATHGoogle Scholar
  14. Smith JO (2007a) Example of overlap-add convolution. In: Spectral Audio Signal Processing, Center for Computer Research in Music and Acoustics (CCRMA), Stanford University [online] Available: http://ccrma.stanford.edu/ ~jos/sasp/Example_Overlap_Add_Convolution.html [14/06/07]Google Scholar
  15. Smith JO (2007b) Dual of constant overlap-add. In: Spectral Audio Signal Processing, Center for Computer Research in Music and Acoustics (CCRMA), Stanford University [online] Available: http://ccrma.Stanford. edu/~jos/sasp/ Example_Overlap_Add_Convolution.html [14/06/07]Google Scholar
  16. Verhelst V, van Compernolle D, Wambacq P (2000). A unified view on synchronized overlap-add methods for prosodic modifications of speech. In Proc. ICSLP2000, 2: 63–66Google Scholar

Copyright information

© Springer Science+Business Media New York 2009

Authors and Affiliations

  • T. Dutoit
    • 1
  • J. Laroche
    • 2
  1. 1.Faculté Polytechnique de MonsBelgium
  2. 2.Creative Labs, Inc.Scotts ValleyUSA

Personalised recommendations