Remember back those days in the seventies, a human was the interface that the computer supported? 

Today we are a step closer!
Converting unfamiliar speech to text in Google Translate is currently an   awkward affair: you have to start a recording and wait until a moment after you're done to find out what the other person said. That's not exactly living up to the dream of a Star Trek-like universal translator, folks. However, the New York Times understands that Translating tools are about to get considerably smarter. Reportedly, an updated version of the mobile app (coming "soon") will automatically detect speech and translate it right away. All you'd really have to do is hold your phone up with the app running; important if you'd rather not go through a song-and-dance routine just to find out where the washrooms are.

 Google says its Translate app can now act as an interpreter, with the addition of a real-time voice-translation mode. It said the updated app would automatically recognise languages being spoken and translate them.

The update, launched on Wednesday January 14th 2015, also allowed users to instantly translate messages using their phone's camera.
But one academic said it would fail to understand the more complex linguistic tools. For basic things, it might be very useful. My mother, for example, does not speak any other languages, but loves travelling, so she could find her way around a town. But it is never going to pick up the nuances, the cultural references or the humour," said Ariane Bogain, a senior lecturer in modern foreign languages at the University of Northumbria.

Different mobile phone providers say the updates took people one step closer to turning [their smartphone] into a universal translator and to a world where language is no longer a barrier.
Limitations:
While she acknowledged the app's usefulness to holidaymakers struggling with the language. But it is no way that major events, such as an EU summit, shall begin using it in the near future. Online translations conveyed the rough message - but you are going to lose a lot in the translation. The limits are that one word can have various meanings, depending on the context, and I do not think that online translation tools are there yet. But it is coming especially when for exemple shopping malls alleles are mapped and context is given trough GPS localization.
When lecturers ask students to hand in translations, one can immediately spot who has used a translation tool because the phrasing is not natural. The message is roughly there, but something is lost. As of today I do not think on line interpretation it is going to replace fifteen years of training.
Skype already manages a similar feat on Windows 8.1, and Japan's DoCoMo showed this off on phones a while back. The concept isn't entirely new, then. With that said, Google's approach may be more helpful for your tourist expeditions simply because it combines extensive cloud translation technology with an easy-to-find mobile app. And no, the automatic interpretation shouldn't pose a security risk. Google splits conversations into separate files, so spies and thieves can't easily figure out who said what. IBM had back in 2000 a global advertisement showing a turkish and english specking person having a conversation over the phone without the intervention of a human interpreter.
Back when windows XP was running one could combine voice recognition, transfert into texte, automatic translation, a reader and it was the same. It was available but no one tried to combine end to end on a commercial basis until recent years.

The limits are that one word can have various meanings, depending on the context, and I do not think that online translation tools are there yet.
As lecturers, when we ask students to hand in translations, we can immediately spot who has used a translation tool because the phrasing is not natural. The message is roughly there, but something is lost.
I do not think it is going to replace 15 years of training.
Just wait until computer power goes to Optical or photonic computing. Just have a look at latest johnny depp movie transcendance and get the hint.

Other voice translation apps are already on the market, Japanese mobile phone providers offered the service since 2013 as a pilot and Skype launched the function december 2014.

more : BBC
& New York Times