I don't see it as that big a deal. There is the disadvantage of being heard in a 10 mile radius, and who says that there HAS to be a creature immune to a spell to make it 'balanced'?
How many creatures are immune to magic missile? (Obviously we are not talking SR, since that works against everything, including sonic blast)
No one spell will ultimately work well in every situation.
You probably won't be doing any sonic blasts while climbing up the side of a mountain laden with snow, for obvious reasons.
If it seems overused, so be it. The same argument could be made for all sorts of other spells that are quite handy.
And there can always be a nemisis immune to it.
![Wink ;) ;)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
(Like the Hero game I heard about where there was a superhero who put ALL of his points into a 'presence attack' - essentially, he is just so darn IMPRESSIVE that his mere presence is enough to demoralize bad guys and even supervillains into giving up immediately. 'Oh my GOD, it's HIM!' He had absolutely NO other abilities. His arch-nemesis was a villain who had absolutely no powers or skills except an immunity to presence attacks. Needless to say, it was always fun when they got to meet.