Tinnitus (which I have due to a diving _faux pas_) is not necessarily
a pure tone - if one (or a few adjacent) nerve cells are damaged and
fire spontaneously (though apparently the same effect happens if they
are damaged and therefore do *not* fire at all), they do not directly
map to frequency, pure tone mapping requires post-processing contrast
enhancement further on in.  Thus "pink" noise counter-stimulus is more
appropriate than a pure tone.

  Also, tinnitus usually self-cancels (mine does, unless you remind me
of it), implying that severe persistent tinnitus requiring masking
devices is actually a breakdown in the brain, not the ear. Thus treated
with anti-epileptic, anti-psychotic or antidepressant medication.

  Speaking from personal observation, I believe everybody knows what
tinnitus is because everyone gets it.  Can anyone tell me they never
have experienced a sudden "airy" whistle in their hearing which they
knew was spurious, but which faded away in a minute or so and was
forgotten.  This could signal the random, spontaneous demise of a
neurone somewhere in the system, just like the sharp spurious pain in a
limb or other body part and similar in other senses.  Alternatively, it
may not be actual neurone death, but a localised, trivial, epileptiform
phenomenon.
--
  Cheers,
        Paul B.

I have certainly had this several times in my life.  From either clubs with ridiculously high sound pressure levels, which made my ears ring for days after, or from stupidly using power tools with no protection.  I'm sure that I've read that any tinitus resulting from exposure to loud noise was a sure sign that your hearing had been irreversably damaged.  However, I had to take a hearing test a few years back go get a track saftey certificate to allow me to work near railway tracks.  The doctor who performed this said my hearing was almost perfect and much better than normal for my age.  As the yanks say, go figure.

Mike