Voice search in Android 4.x requires proprietary libs only available for ARMv7. Workaround is to use old gingerbread voice search app and special 'voice search for google now' app. You can only the use the voice search that you find in your app drawer.
A newer version of the 'voice search for google now' app (now called 'voice search assistant') can link the mic in google now widget to itself. It is a paid solution though and I haven't tested it.
WELL I PUCHASED THE APP AND AFTER BEING DISAPPOINTED I SERCHED IN THE DEVELOPER FORUM
and this is the answer from the developer itself:
You will be able to use voice search with Google Now, but not directly within, as on ARMv7. You will have to go through my app to pass the voice command to Google Now. But there is a desktop shortcut available, and on most devices, it can also be associated with the homescreen search widget, so it is basically zero effort solution. As long as you do not need to make another voice command while already in Google Now - you will have to leave it first or just type the query.
SO BASICALLY THE HOME SCRREN PERSISTENT SERACH MICROPHONE DOESN'T WORK AND AFTER SEARCHING STH THE MICROPHONE WITHIN GOOGLE NOW DOESNT WORK NEITHER
I don't know what this app is doing but i had exactly the same result using voice search app from app drawer and it needs voice search anyway to work !
Edited by Cata_Simi, 30 March 2013 - 02:30 PM.