Effect of conductive hearing loss on central auditory function.

INTRODUCTION: It has been demonstrated that long-term Conductive Hearing Loss (CHL) may influence the precise detection of the temporal features of acoustic signals or Auditory Temporal Processing (ATP). It can be argued that ATP may be the underlying component of many central auditory processing capabilities such as speech comprehension or sound localization. Little is known about the consequences of CHL on temporal aspects of central auditory processing. OBJECTIVE: This study was designed to assess auditory temporal processing ability in individuals with chronic CHL. METHODS: During this analytical cross-sectional study, 52 patients with mild to moderate chronic CHL and 52 normal-hearing listeners (control), aged between 18 and 45 year-old, were recruited. In order to evaluate auditory temporal processing, the Gaps-in-Noise (GIN) test was used. The results obtained for each ear were analyzed based on the gap perception threshold and the percentage of correct responses. RESULTS: The average of GIN thresholds was significantly smaller for the control group than for the CHL group for both ears (right: p=0.004; left: p<0.001). Individuals with CHL had significantly lower correct responses than individuals with normal hearing for both sides (p<0.001). No correlation was found between GIN performance and degree of hearing loss in either group (p>0.05). CONCLUSION: The results suggest reduced auditory temporal processing ability in adults with CHL compared to normal hearing subjects. Therefore, developing a clinical protocol to evaluate auditory temporal processing in this population is recommended.