Prof Moore's Digital Voice Factory

Coordinator –  Roger Moore

 The Exhibit -

• Learn to talk backwards:  Lets you record some speech, listen to it backwards and then attempt to reproduce what you’ve heard.  With practice it’s possible to create sounds that, when reversed, sound like normal speech.  Start with something simple first – a short word or your name.
• Speak like a Dalek:  Lets you record some speech and have it played back as if spoken by one of Dr. Who’s Daleks.  This works particularly well if you speak on a monotone.
• Have fun with your voice:  Lets you record some speech and play around with how it sounds by changing the speed, pitch, modulation and echo.  See if you can change your voice to sound like Miss Piggy from the Muppets or a Cyberman from Dr. Who.
• Sound like a robot:  Lets you record some speech and have it played back as if spoken by a robot.

 The Technology - The main technique underlying Prof Moore’ Digital Voice Factory is a principle known as phase vocoding.  Vocoding - short for voice coding - is the name given to a whole range of methods for analysing speech sounds and converting them into a digital electronic form that can be re-synthesised back into speech.  All mobile phones use a vocoder.  A phase vocoder is a particular type of voice coding that allows the digital signals to be manipulated in various ways, for example slowing it down or speeding it up without changing the pitch of the voice.  The basic algorithm uses the fast Fourier transform (FFT) - a standard method for calculating the energy present at different frequencies.  Phase vocoding was introduced in 1966 by Dr. Jim Flanagan of Bell Laboratories in the USA, and it’s widely used in the music industry – particularly in the commercial voice pitch correcting software Auto-Tune.