Tinnitus

Tinnitus is a phenomenon of the nervous system connected to the ear,
characterized by perception of a ringing or oscillating (often percepted as
sinusoidal) sound in the ears. This sound may be quiet, or loud enough to
drown out all outside sounds. Tinnitus can be caused by the following
things:

   * A sudden loud noise,
   * Hearing loss (20 per cent of cases: chronic noise damage and
     presbycusis),
   * Head injury (especially basal skull fracture),
   * Drugs: aspirin overdose, loop diuretics, aminoglycosides, quinine,
   * Temporomandibular and cervical spine disorders,
   * Suppurative otitis media (also chronic infection and serous OM),
   * Otosclerosis,
   * Ear wax,
   * Meniere's disease,
   * Impacted wisdom teeth,
   * Hypertension and atherosclerosis,
   * Acoustic neuroma,
   * Palatal myoclonus (objectively detectable),
   * Arteriovenous fistulae and arterial bruits (objectively detectable),
   * Severe anaemia and renal failure,
   * Glomus jugulare tumours (objectively detectable),
   * Stress and depression

Some types of tinnnitus can be treated while others become permanent and
very annoying to its host. Under these circumstances, silence become
painful, and the host may have to generate artificial noise that drowns the
tinnitus sound in order to fall asleep.