I have the Sync/Nav unit and I keep my music on a 32GB stick as .mp3s in the glove box via cable plugged into the USB2 port in rear of the radio unit. Voice commands to call up songs are intermittent, even though I have gone through the procedure to tune it to my voice. For example, PLAY TRACK "HEY JUDE" works great, but some other songs by voice command, SYNC just doesn't find them at all. If I go through the menu, I can see and play the songs by selecting from the screen.
Was browsing the TSBs and this one seems to address the issue. Has anyone had this TSB done and how did it work? Not sure I want the dealer to monkey with it and make it worse as all of the other important functions by voice work fine (phone, set temp, fan speed etc.) Comments appreciated.
TSB 11-6-9

06/15/11

SYNC - INTERMITTENT VOICE RECOGNITION

FORD:
2011 Fiesta, Focus, Fusion, Mustang,
Taurus, E-Series, Escape, Expedition, F-150,
F-Super Duty, Flex

LINCOLN:
2011 MKS, MKZ, MKT, Navigator

MERCURY:
2011 Milan, Mariner

ISSUE
Some 2011 vehicles equipped with SYNC(R) may exhibit intermittent voice recognition: SYNC(R) is not listening/hearing commands, no response to voice commands or SYNC(R) responds voice commands not available with this device when using play artist/album/track commands.

ACTION
Follow the Service Procedure steps to perform software update.