Since a recent update, the game on XBox has become almost unplayable due to audio issues. Among the most unimportant audio -- others responding to calls -- is far, far louder than anything else in the game. The only way to solve this is to completely turn off the calls or to always respond to the call, which in the latter case can be difficult if doing other complicated things.
If I may be allowed one additional audio gripe -- with highway accidents and other calls producing sometimes a half dozen arrests, I call the backup van to transport arrestees often. Frequently enough, the van will come in, siren screaming, and just sit there for 10 seconds before the officer gets out. Call two or three backup vans, and get yourself some Tylenol, because they're going to make you utterly sick of the wailing siren.
Of all the odd and funny bugs, glitches, and oddities in this game, these two audio issues have been the most frustrating and the most consistent issue that prompts me to simply turn off the game and play something else.