The word "KaleiVoiceCope" comes from combining the words Kaleidoscope and Voice. A kaleidoscope is a tube-shaped optical instrument that is rotated to produce a succession of symmetrical designs by means of mirrors reflecting the constantly changing patterns made by bits of colored glass at one end of the tube. The idea here is to replace the bits of colored glass by the human voice, so a KaleiVoiceCope is used to transform the voice character, tone, pitch, gender, timbre, etc based on a set of controllable parameters.

The KaleiVoiceCope Technology consists in a Software Library containing state of the art signal processing algorithms that convert and modify the human voice, based in a set of meaningful controls that preserve its natural quality.

These meaningful transformations include adding vibrato, changing fundamental frequency or amplitude, controlling spectral and physical characteristics of the voice or modifying timbre. High-Level Presets based on these transformations can be easily created to allow, for instance, gender change transformations, convert to operatic voice or robotizer effect.

This Voice Transformation Library can be easily integrated in post-production studios or software FX plug-ins to transform isolated singing or speech voices from a song, film or advertisement or even generate new virtual characters from existing ones.


Use cases and applications

  • Modify the timbre and characteristics of an actor’s voice
  • Interactive installation where the user transforms his/her voice characteristics in real-time (educational purposes)
  • videogames
  • Available transformations: Man, woman, kid, old, monster, robot, alien, clown.

Available software tools

  • VST Voice Transformation Plug-in (Windows, OSX)
  • Interactive installation for CosmoCaixa Museum (Windows, touchscreen)
  • Interactive installation for CosmoCaixa Museum (WIndows, physical buttons)

System requirements

Standard PC


SALERO EU project

Team involved

Jordi Bonada, Oscar Mayor, Jordi Janer

Commercialization options

This technology is licensed to our spin-off company Voctro Labs


Oscar Mayor <[email protected]>



The KaleiVoiceCope technology can be applied to a wide range of fields from professional audio Fx software for voice manipulation to entertainment, being also applicable for exhibitions or videogames. The technology has been already applied in some products and exhibitions, click on the left panel to get more information about products and exhibitions featuring the KaleiVoiceCope technologies.



Mayor, O. Bonada, J. Janer, J. 2010.
'KaleiVoiceKids: Interactive Real-Time Voice Transformation for Children'
Proceedings of 9th International Conference on Interaction Design and Children; Barcelona, SPAIN


Mayor, O. Bonada, J. Janer, J. 2009.
'KaleiVoiceCope: Voice Transformation from interactive installations to Video-Games'
Proceedings of 35th AES Conference: Audio for Games; London, UK

Bonada, J. 2009.
'Voice Processing and Synthesis by Performance Sampling and Spectral Models'
PhD Dissertation, UPF; Barcelona, SPAIN


Bonada, J. 2008.
'Wide Band Harmonic Sinusoidal Modeling'
Proceedings of 11th International Conference on Digital Audio Effects DAFx-08; Espoo, Finland


Loscos, A. 2007.
'Spectral Processing Of The Singing Voice'
PhD Dissertation, UPF; Barcelona, SPAIN


Loscos, A. Bonada, J. 2006.
'Esophageal Voice Enhancement by Modeling Radiated Pulses in Frequency Domain'
Proceedings of 121st Convention of the Audio Engineering Society; San Francisco, CA, USA


Loscos, A. Bonada, J. 2004.
'Emulating Rough And Growl Voice In Spectral Domain'
Proceedings of 7th International Conference on Digital Audio Effects DAFx'04; Naples, ITALY

Bonada, J. 2004.
'High Quality Voice Transformations Based On Modeling Radiated Voice Pulses In Frequency Domain'
Proceedings of 7th International Conference on Digital Audio Effects DAFx'04; Naples, ITALY

Fabig, L. Janer, J. 2004.
'Transforming Singing Voice Expression - The Sweetness Effect DAFx'04'
Proceedings of 7th International Conference on Digital Audio Effects; Naples, ITALY