The Principal Designer for Google Search, Jon Wiley, recently took part in a AMA (Ask Me Anything) discussion on Reddit, where he was asked to share a few things Google was currently working on. He mentioned that they are working on a new feature for Voice Search that will allow someone to ask a question in one of multiple languages, without reconfiguring your “native tongue” every time. So if you spoke English and Spanish you can alternate and Google with adjust it automatically.
Google currently translates Voice Search is noted based on the default language that is set for other Google Services.