Can you identify a voice that passes through a voice changer?

Most of the time it is unidentifiable.

If you had an exact copy of their voice changing software and knew it was an exact copy then you could run the voice through an inverse circuit based on the original and change it back to the original voice with little loss or distortion. But, you have to have the EXACT circuit or it won't work.

Yes you can identify it by two different ways.

Firstly you can listen to the speech patterns and very often identify someone you know in this manner. This involves listening to the spacing between words, the vocabulary used and its syntax.

The other more high tech way is to reverse the process of the voice changer. The cheapy voice changers will do something generic to the sound which can be reversed in an edit suite. It is easier if you know what has been done to it however it is not impossible to do it by educated guesswork. It is similar to the way that photos of people who are supposed to be annonymous used to have a swirl effect applied to them to make them unidentifiable. This was proven to be ineffective when people simply reversed the process on a home computer. Now a black block is used. If you want to make it harder to identify a voice then you should do two other things on top of using a voice changer, playing white noise alongside the voice when it is being changed and also white noise as it is being played. Other sounds can help too however they can usually be identified and removed or reduced to make the sound clear enough for identification. Ideally what you should do is use a text to speech program which will bear no relevance to your voice (although your vocabulary and some syntax may still be identifiable if someone knows you).

Voice modulation is just a Fourier transform (or series of transforms). If you knew the reverse transforms, you could get the signal (original voice) back albeit with a bit of noise. The problem is knowing the reverse transform (or figuring it out) and subtracting out the noise.

you can if you know the algorythm the voice changer uses to change your voice, but they would have to know the brand and model