The phonetic processor was a piece of technology, part of the universal translator.
In 2151, Hoshi Sato needed to run Klaang's Klingonese dialect through the phonetic processor so the UT could properly translate. (ENT: "Broken Bow")
Later that year, the phonetic processor had trouble locking onto the Axanar language. Sato then had the processor search for synonyms of "pump". (ENT: "Fight or Flight")