I don't suffer from it but I do notice a ringing sound when in a dead silent room, it has to be utterly dead silent though. I typically sleep with a fan on for background noise because I wake easily from small noises and that completely eliminates me hearing the ringing sound, but I'm sure my case is extremely mild. A fan or other white noise generator might help your wife, you'd never be able to exactly duplicate the sound she's hearing because it's not a sound that's being generated, it's a nerve problem. Even if you were able to exactly duplicate and invert the frequency that she appears to be hearing the nerve ghost noise would be over ridden by the real sound. In order to properly cancel it out you'd have to actually cancel out the nerve impulses that are causing it, and that's not physically possible.