Speech is so commonplace that we often forget that the characteristics of our voices are quite distinctive. Voice recognition systems authenticate actual voices, as opposed to speech recognition, which asks a user for a specific password. Instead, the voice itself - its tone and timbre is the password, and the technology is used to authenticate identity through digital comparison against a database.

Joining or enrolling in a voice recognition system may take a little time, since the user must teach the computer by speaking a number of phrases, but after this initial phase the technique may be used quickly and efficiently to secure facilities or verify time and attendance. Only ambient noise limits its application.