Earphone

Spock with earphone

Spock with earphone, 2265

The earphone was a personal speaker connected to the bridge science station of the USS Enterprise. Consisting of a flexible cable with a receiver, this device was placed next to the scope on the console. A person would use this device by holding it against their ear. It was later replaced by an earpiece.

In 2265, with the receiver to his right ear, Spock reported what he was hearing from the disaster recorder of the SS Valiant to the bridge crew and department heads. (TOS: "Where No Man Has Gone Before")

This technology was named in the final revised draft script for the episode. [1]