I went to a Nazareth concert last summer, and due to enormous amplification and horrible acoustics I'm sure I got hearing damage,
resulting in minor high pitch tinnitus and not being able to hear anythig above 17Khz (I'm 32).
So this summer, when I got Dream Theater tickets, I did some research and ordered those:
http://www.elacin.co.nz/erflexcomfort.html.
These are custom made filters that clam to have flat attenuation, similar to just lowering the volume dial of an aplifier.
Unfortunately I had to cancel the order due to delays and other various reasons, so I can't comment on their actual performance.
They're not cheap though.