People have a rather poor memory and recognition of voices they're not familiar with. By the time it's been through cellphone codecs (linear predictive coding t

People have a rather poor memory and recognition of voices they're not familiar with. By the time it's been through cellphone codecs (linear predictive coding that basically resynthesises your voice using a handful of parameters) it's a wonder we can tell one speaker from another. How we do it is to listen for other features of speech, accent and vowels, speed, rhythm, prosody, intonation, anomalies like glottal noise, dropped H's, nasal formant, murmuring diphongs.. the things that make us unique. Impressionists (mimics) learn those. If they're not present in the source signal it's not easy to change or add them unless you move the whole signal to an intermediate form (speech to text) and then resynthesis the whole show (TTS) via a full articulation model that has those anomalous features. If you get any good at this the people who you will piss-off are banks and folks who use voice as a blind authenticator (hint: your bank already does if you call them).