| Tinnitus is a hearing disorder most commonly known as "ringing of the ears" which affects an estimated 15--20% of the general population. Currently there is no cure, nor standardized way to characterize it. Here we investigate methods of tinnitus suppression through electric stimulation of the auditory nerve, looking at effects of stimulation rate, stimulation place, and stimulation level on suppression of tinnitus in patients with cochlear implants (Experiment 1). The majority of subjects (∼60%) experienced tinnitus suppression to at least one presented combination of stimulation rate, place and level. There appear to be two groups of subjects, "Responders" and "Non-Responders," where (1) subjects who respond to one stimuli are significantly more likely to respond to a second stimuli, and (2) subjects who exhibit tinnitus suppression to our tested stimuli also exhibited a higher degree of loudness adaptation as compared to subjects whose tinnitus did not respond to the stimuli tested here. We subsequently developed two computer-based procedures to achieve an accurate and efficient psychophysical characterization of tinnitus in subjects with acoustic hearing (Experiment 2). The first tinnitus matching method was a thorough, controlled and fully randomized "adaptive" procedure, while the second was a flexible, user-controlled "adjustment" method. Both procedures were compared to a standard "Classic" procedure based on previous methods developed by Vernon and Meikle (1988). Here we show that that (1) pure tones are not sufficient to match a given subset (∼30%) of tinnitus subjects, (2) incorporating the additional acoustic dimension of bandwidth improves the similarity of the tinnitus match to the subject's tinnitus in the majority (95%) of subjects, and (3) adding the dimension of bandwidth improves the precision of the matched tinnitus center frequency as compared across methods. We will conclude by discussing insights from our results and exploring future directions of this tinnitus work. |
