Universal Translator
The Universal Translator (also referred to as a "U.T." or translator circuit) is a device used to decipher and interpret alien languages into the native language of the user.
On Earth, the universal translator was invented shortly before 2151, and was still experimental at the time of the launch of Enterprise. (ENT: "Broken Bow") This version of the UT could be used for ship-to-ship communications only, and face-to-face communication or off-world missions required the use of a skilled linguist - in Enterprise's case, Hoshi Sato - notably in situations where reading alien languages on the control panels, hatches, and displays were involved. (ENT: "Sleeping Dogs", "Vox Sola") A new language can quickly be translated in person-to-person encounters by having one speak his or her language. Sato also created the linguo-code translation matrix in order to anticipate and speed up the translation of new and unknown languages. (ENT: "In a Mirror, Darkly")
By 2155, the UT had been miniaturized into a smaller self contained version that could be worn on clothing and provide for personal communication face to face. These portable translators continued to have a similar physical design for at least the next 110 years, however becoming more wand-like by 2267. (ENT: "Demons")
It was in 2267 that Captain Kirk of the USS Enterprise used one to communicate with the alien known as the Companion in the Gamma Canaris region. Responding to Zefram Cochrane's question about the theory of operation, Kirk explained that there are certain universal ideas and concepts common to all intelligent life. The translator compares the frequencies of brainwave patterns, selects those ideas it recognizes, and provides the necessary grammar. Kirk further explained that the device speaks with a voice, or the approximation of one, that corresponds to the identity concepts it recognizes. The Companion was revealed to be female because the universal translator detected this facet of its identity from its brainwave patterns, and assigned it a female voice. (TOS: "Metamorphosis")
The universal translator was able to translate the language of the sentient nanites, created by Wesley Crusher in early 2366, into binary language. (TNG: "Evolution")
In the 24th century, UT technology had advanced to where it could be integrated into the commbadges worn by Starfleet personnel. (VOY: "The 37's")
The universal translator fails from time to time. For example, it was capable of translating the literal words of the Tamarians into English, but it was unable to translate the Tamarians metaphorical manner of speaking into easily understandable speech. The translator also missed the nuances of various transitive tenses of Dominionese. (TNG: "Darmok"; DS9: "Statistical Probabilities")
Another language the UT had trouble deciphering was that of the Skrreeans. Several hours were required to record and analyze the language before a proper translation form was created. (DS9: "Sanctuary")
The universal translator can be detected when it is used to process language in communications. In the 23rd century, sometime between stardate 9522 and 9529, Commanders Chekov and Uhura were forced to revert to manually translating their speech using a paper dictionary into Klingon in order to surreptitiously get them past the border. Uhura successfully used very broken Klingon to describe the USS Enterprise-A as a freighter, the Ursva, headed to Rura Penthe to deliver supplies. The use of paper dictionaries was explained by Chekov as necessary because the use of universal translator would have been recognized. (Star Trek VI: The Undiscovered Country)
The universal translator's capabilities are focused on interpreting the brain patterns of humanoid lifeforms. For entirely non-human lifeforms, such as the cytoplasmic lifeform which attached itself to B'Elanna Torres, the universal translator is completely stymied. (VOY: "Nothing Human") For the same reason the UT is unable to translate foreign languages spoken by holodeck characters. Kathryn Janeway is unable to understand her charges' use of Latin in the holodeck. (VOY: "Learning Curve")
At one time while Neelix was negotiating with a xenon-based lifeform, the UT went off-line and Arturis saved him from embarrassment by translating the alien's words. (VOY: "Hope and Fear")
Ferengi translators evolved from hand-held devices in the 22nd century (ENT: "Acquisition") into small devices inserted into the ear. These later models were easily disrupted by nuclear fusion radiation. (DS9: "Little Green Men")
Cardassian universal translators have to be manually adjusted in order to properly translate the Breen language. (DS9: "Strange Bedfellows")
Background Information
The universal translator is one of many Star Trek technologies that exist primarily as conventions to aid storytelling. The workings of the UT enables the vast majority of dialog between characters to be written (and delivered) in English, to the convenience of viewers and writers alike. Writers do not have to devise a new language for each new alien of the week that speaks on-screen, and viewers do not have to watch for subtitles.
Another storytelling conceit is that the device makes non-English speakers appear as if they're speaking English. That is, lip movements match English language pronunciation. This "convention" is particularly obvious in episodes, like ENT: "Civilization", "Acquisition", "Precious Cargo" and DS9: "Little Green Men", in which the universal translator is off-line for periods of time. Were the device real, it would more likely have an effect similar to watching a movie dubbed into another language.
The draft proposal Star Trek is... mentions this concept:
We establish a "telecommunicator" device early in the series, little more complicated than a small transistor radio carried in a pocket. A simple "two-way scrambler", it appears to be converting all spoken language into English. (Roddenberry 11)
