Hola buscando por ahi, encontre esto:
"OK, I've found the solution.BEWARE! doing this also resets all the home screen short-cuts & widgets to default (but not the wallpaper strangely). - This may not be the case if you run a third party launcher but I've not tried that.
Go to Settings>Apps > All > 'Google Search' and press the 'Uninstall Updates' button, which will after confirmation will reset it to the factory settings.
You may want to disable automatic updates in the play store to stop the fix being undone.
Since doing this, voice dial over Bluetooth seems to work perfectly. Not sure what other 'improvements' I lost but it's nothing obvious.
Hope this helps.
EDIT: As of the update to Google Search on 10th December 2013 voice dialling seems to be back to the same level of 'working' as the factory default. (there are still some contacts it can't understand but it's no longer utterly useless). It's safe to turn auto-update back on."
Fuente:
http://productforums.google.com/foru...g/9u51DJ1PXHkJ
Un saludo