2The Ringing in Silence: Tinnitus in the Deafened Ear

FSound from nowhere

Tinnitus is the perception of sound, usually a ringing, hissing or buzzing, when no external source is producing it. The subjective kind that concerns us here is heard only by the patient, distinguishing it from rare objective tinnitus caused by a real internal noise such as turbulent blood flow. It is one of the commonest complaints in ear practice and rises steeply with age and with hearing loss. Far from being a minor curiosity, severe tinnitus is among the most distressing symptoms a patient can carry, precisely because it never stops and cannot be switched off.[2004]

FWhy deaf ears ring so often

Tinnitus is strikingly common among cochlear implant candidates: across studies, roughly two-thirds to more than eighty percent of people with severe-to-profound hearing loss report it. The central explanation is deafferentation: when the damaged cochlea stops feeding the brain its normal signal, central auditory neurons compensate by turning up their own gain. With less inhibition restraining them, these over-amplified neurons begin to fire in patterns the brain reads as sound, even though nothing is arriving from the ear. This is why tinnitus is generated centrally even when it is triggered peripherally, and why cutting the cochlear nerve does not reliably cure it, and may worsen it. The model has a hopeful corollary: if loss of input drives the gain up, restoring input should be able to bring it back down.[2004][2004]

CThe cost of a sound that never stops

Bothersome tinnitus erodes sleep, breaks concentration, and is tightly linked to anxiety, low mood and reduced quality of life. For some deaf patients the ringing is the dominant complaint, more disabling than the loss of hearing itself. Because the distress is psychological as much as sensory, two people with identical loudness can report wildly different handicap. This gap between measured loudness and lived suffering is exactly why we need handicap questionnaires, not loudness alone, to capture the burden.[1996]

TPutting a number on a phantom

Psychoacoustic matching estimates the tinnitus by asking the patient to match its pitch and to balance an external tone to its loudness. Loudness and pitch matches reveal that most tinnitus sits in the high frequencies, mirroring the region of greatest hearing loss. The Tinnitus Handicap Inventory, a 25-item questionnaire scored from 0 to 100, is the most widely used measure of how much the tinnitus actually disrupts life. Simple visual analogue scales, where the patient marks loudness or annoyance on a 0-to-10 line, give a quick repeatable read for tracking change after treatment. Using the same tools before and after implantation is what lets us prove the device truly quietened the ringing rather than the patient merely getting used to it.[1996]