Psychophysical Tuning Curves and Extended High Frequency Audiometry Findings in Individuals with Normal Hearing Having Tinnitus

Abstract

Tinnitus is one of the most common problems confronted in routine audiology practices. The occurrence of tinnitus in the absence of audiometrically detectable hearing loss poses a challenge to the clinicians as the exact pathophysiology behind this phenomenon is not clearly established. A detailed audiological assessment is essential as the origin of tinnitus can be at any level within auditory system. This study aimed at characterization of the psychophysical tuning curves (PTCs) and Extended High Frequency Audiometry (E-HFA) in individuals with normal hearing having tinnitus. The PTCs and E-HFA were administered on 20 adults with a complaint of tinnitus having normal hearing sensitivity and the results were compared with that of individuals with normal hearing sensitivity without tinnitus. The results showed no difference in Q10 values between the two groups. The tip frequencies of PTCs of individuals with tinnitus were significantly different from that of individuals without tinnitus at 4000 Hz and 6000 Hz; indicating a cochlear lesion. The E-HFA thresholds were elevated in individuals with tinnitus; which is suggestive of damage corresponding to these frequencies. Overall findings indicated the presence of pathology at the level of basilar membrane, which remained hidden in conventional audiometry; more likely to be inner hair cell damage at frequency regions corresponding to 4000 Hz and above on the basilar membrane. The study signifies the inclusion of PTCs and E-HFA in individuals with tinnitus so as to track the underlying lesions which remain hidden in conventional audiometry.