The computer voice is an audio interface program designed to allow computers to express information verbally. Many civilizations, such as the Federation and the Cardassian Union, equip their computers with this feature.

The computer voice of the USS Enterprise was reprogrammed in 2267 on Cygnet XIV, with the intent on giving it a less mechanized personality. The resulting modifications caused the computer to address Captain James T Kirk in an increasingly amorous manner.

(TOS: "Tomorrow is Yesterday")

During reorganizations of Deep Space 9's computer in 2369, Chief Miles O'Brien experienced diffculties because of the previously Cardassian programmed computer systems. The female computer voice told him to read the Cardassian operational guidelines and refused to follow his commands. When Commander Benjamin Sisko reminded O'Brien that this is "only" a computer, O'Brien answered "She's no computer, sir. She's my arch enemy."

(DS9: "The Forsaken")

The computer voice on most Federation starship and fixed installation computers has been portrayed by Majel Barrett Roddenberry since the early days of The Original Series (with the exception of some early The Next Generation). The computer voice in TOS was very rhythmic and mechanical. In the later series it became a far more normal-sounding female voice.

The computer voice on the ISS Enterprise in the mirror universe was provided by John Winston, the actor who portrayed transporter chief Kyle.

(TOS: "Mirror, Mirror")