They were commonly used security methods to identify individuals when accessing critical or secured information, including on turbolifts. They had (for the most part) replaced retinal scans between the 21st and 24th centuries. In the 23rd century, a voiceprint was a primary part of the Steinman analysis method of comparing someone against their baseline retained in Starfleet personnel files. (TOS: "The Lights of Zetar" ) Voiceprint authorization is required to open a code 47 encrypted communication channel. (TNG: "Conspiracy" )