Yeah... I've noted that without jailbreak (on a 3.50 console... using the original disc of course) there are sound problems in the "Pratice arena"... many strikes don't do any sound and also slams on the mat aren't doing any sound. During "normal" matches there's no problem as far as I could test... So there might indeed be a problem with the game itself :(
Also if you're testing, the first missing sounds are when the savegame is loaded... when you have to press "X" with the original disc it does a "woosh" sound but with jailbreak it doesn't. (Just to say it's not needed to go until the loading screen which freeze somtimes with JB to test if it works or not).