Telephone voice changer – DIY project

Posted: March 23, 2011 in Uncategorized
Change your voice over the phone in real time using a computer or digital processor.

Figure 0 - This black box allows routing effects through your phone system

This black box allows routing effects through your phone system

This project converts an old desktop telephone into a versatile audio mixing station that lets you route your telephone calls through an effects processor in order to create a state of the art voice changer. By using a real time computer voice filter or a professional quality effect box, you can change your voice in ways that will make you sound like a completely different person. You can make a man sound like a woman, or a girl sound like a man, or a man sound like an elderly lady, or any possible combination imaginable with results that will fool anyone.


Unlike those “spy toy” voice changers that make you sound like a funny cartoon, a real vocal effects unit or computer vocal filter will alter a voice in a perfectly convincing manner, allowing fine control over both the formant (gender) and the pitch of your voice. Sure, you can have a lot of fun with evil and chipmunk voices as well, but if you really want to mask your voice identity in a convincing manner then this useful device will allow you to connect any microphone compatible audio processing unit into your phone so you can alter your voice in real time.


There are many extremely powerful audio processing programs available for a computer that allow a person to alter his or her voice by talking into a microphone. Many of them are inexpensive or even free. Music stores also offer digital effect boxes that are designed for vocal processing, and these have the same functionality as the computer programs, but do their processing in a dedicated DSP (digital signal processor). I will be using both the computer software voice changer as well as the “effect box” version of the vocal processor to show how each one can be connected to the phone system using this project.

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