For the past four years, scientists at Commerce's National Institute of Standards and Technology (NIST) have been conducting detailed performance evaluations of speech translation systems for the Defense Advanced Research Projects Agency (DARPA). Previous systems used microphones and portable computers. In the most recent tests, the NIST team evaluated three two-way, real-time, voice-translation devices designed to improve communications between the U.S. military and non-English speakers in foreign countries.
Traditionally, the military has relied on human translators for communicating with non-English speakers in foreign countries, but the job is dangerous and skilled translators often are in short supply. According to NIST’s Brian Weiss, the DARPA project, called TRANSTAC (spoken language communication and TRANSlation system for TACtical use), aims to provide a technology-based solution. Currently, the focus is on Pashto, a native Afghani tongue, but NIST has also assessed machine translation systems for Dari—also spoken in Afghanistan—and Iraqi Arabic. 
All new TRANSTAC systems all work much the same way, says project manager Craig Schlenoff. An English speaker talks into the phone. Automatic speech recognition distinguishes what is said and generates a text file that software translates to the target language. Text-to-speech technology converts the resulting text file into an oral response in the foreign language. This process is reversed for the foreign language speaker. Read more  | video