What determines the 'innate signature' of a person's voice?

Question

You can have two men who have grown up in the same country and place (let's take south London in the UK for example) who are the same age, went to the same schools, and the same pitch (depth) in their voice but if you recorded both their voices and played them to strangers, you can tell that their different people.

I've heard that it's the 'timbre' that determines a persons voice signature which make their voice sounds the same even if they spoke in a different pitch or accent to their native one.

Is this true?

Answer 1

Timbre is a general term for the properties of any sound. In the case of the human voice, what makes a person recognisable and distinct from other people are the "formants" created by the vocal tract.

These regions in the frequency spectrum that are accentuated by resonance in the throat and mouth, give a voice a particular sound. They enable us to tell e.g. a man's, woman's and child's voice apart, and to identify the voice of a specific person.

When you hear a recording of a voice being played back at faster speed, it doesn't just sound like the same person speaking or singing at a higher frequency. Because the formants are shifted upwards too, the voice will become more feminine, then child-like, and ultimately cartoonish , depending on how much you speed it up.