Google Voice was supposed to work fine without prior training but it seems that the service is still pretty much in an alpha version and available only in US English.
According to Telegraph and Daily Mail, the programme appeared to have been tweaked for American accents only as British users were left confused by the results they were received.
Looking for the term "iPhone" resulted in a wide variety of results ranging from Sex to Sledding (in Scottish accent), to "My sister" or "Einstein" when the request was made with a Kentish accent.
Google has been working on voice search since 2002 and it was issued a patent by the US Patent and Trademark office to cover a "Voice interface for a search engine" back in April 2006
The search giant has yet to launch the voice recognition search tool on the Android platform and it is only a matter of time before other English accents are added to the database.
Google still needs to build more consistent algorithms to cater for a wider range of English used worldwide and you wouldn't discard Google's ability to bring forward a Text to Speech engine fairly soon.