Residual inhibition functions in relation to tinnitus spectra and auditory threshold shift.
CONCLUSIONS
Psychoacoustic functions relating the depth and duration of tinnitus suppression ('residual inhibition') to the center frequency of band-passed noise masking sounds appear to span the region of hearing loss, as do psychoacoustic measurements of the tinnitus spectrum. The results (1) suggest that cortical map reorganization induced by hearing loss is not the principal source of the tinnitus sensation and (2) provide a necessary baseline for optimizing residual inhibition in individual cases.


OBJECTIVE
To measure residual inhibition functions and tinnitus spectra using sounds spanning the region of hearing loss.


METHODS
Three subject-driven, computer-based tools were developed and applied to measure psychoacoustic properties of tinnitus and residual inhibition in 32 subjects with chronic tonal, ringing, or hissing tinnitus. Residual inhibition functions were measured with band-passed noise sounds varying in center frequency up to 12.0 kHz.


RESULTS
The depth and duration of residual inhibition increased with the center frequency of the band-passed noise stimuli. Near-elimination of tinnitus for up to 45 s was reported by 8/24 (33%) subjects at center frequencies above 3 kHz (these cases distributed across tinnitus types). Tinnitus spectra covered the region of hearing loss with no preponderance of frequencies near the audiometric edge of normal hearing.
Roberts
Larry E
LE
Department of Psychology, Neuroscience, and Behavior, McMaster University, Hamilton, Ontario, Canada. roberts@mcmaster.ca
Moffat
Graeme
G
Bosnyak
Daniel J
DJ
D000328:Adult; D000368:Aged; D001299:Audiometry; D001309:Auditory Threshold / Q000502:physiology*; D002908:Chronic Disease; D003936:Diagnosis, Computer-Assisted; D005260:Female; D006311:Hearing Disorders / Q000175:diagnosis / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009433:Neural Inhibition / Q000502:physiology*; D009622:Noise; D010470:Perceptual Masking / Q000502:physiology; D010898:Pitch Perception / Q000502:physiology; D011571:Psychoacoustics; D012720:Severity of Illness Index; D013016:Sound; D014012:Tinnitus / Q000145:classification / Q000175:diagnosis* / Q000503:physiopathology*