systems and methods to authenticate and verify user access replace the digits of a personal identification number of a particular user with prompted randomized words that are to be uttered by an unidentified user . by virtue of this replacement , the pin remains secret . a known speaker provides voice samples to the system in advance . the words uttered by the unidentified user correspond to digits . the uttered words are checked against the pin , and are used to verify if the unidentified user &# 39 ; s voice matches the voice of the known speaker .