The collar translator was a technology in use by the Federation.
Known informally as the 'copycat collar', this device uses universal translator technology to convert speech from one language into another. In addition, the collar translator can modulate the voice of the speaker to duplicate completely the racial characteristics of a desired language. (For example, a human using the collar to converse Klingonaase would sound like a Klingon, rather than a human trying to sound Klingon.) The collar also gives timbre and tone to the voice, unlike the flat, mechanical tone created by the standard translator. The collar consists of a ring-shaped neck unit and a mandibular probe that projects up from the neck unit along the left side of the wearer's jaw. The device uses two standard small-equipment energy cells, good for twelve hours of continuous use. (FASA RPG module: Star Fleet Intelligence Manual: Agent's Orientation Sourcebook)