So I was reading the attached article and I have a technical question. Could a cell phone monitor the frequency/data transmitted level of the voice on the phone? A natural voice falls below the frequency levels of the phones range. Reading this it sounds like to synthesize a voice it is at a much higher level because of everything needed in the algorithm. So could the voice be measured? Natural vs fake?

https://home.work.caltech.edu/~ling/pub/icslp98lsp.pdf