Hearing research news. From the periphery to the center

In the clinical setting, a patient's hearing level is usually quantified by determining the hearing threshold in pure tone and speech audiometry. The measurement and analysis of auditory brainstem responses (ABRs) for quantification of hearing impairment go beyond the scope of routine ENT diagnostic practice. In basic scientific studies, ABRs are commonly used to determine hearing thresholds in animal models. In the last few years, analysis of suprathreshold ABRs, particularly ABR wave I suprathreshold amplitudes, have led to the discovery and understanding of previously undetected hearing impairments in noise-induced and age-related hearing loss models. Deafferentation of inner hair cells and auditory nerve fiber degeneration were identified as pathophysiological correlates to the observed reduction in ABR wave I amplitudes. Such reductions in ABR wave 1 amplitudes could also be identified in chronic tinnitus patients with apparently normal hearing. Recent functional magnetic resonance tomography studies in humans have shown that the limbic system can influence the perception of tinnitus by interacting with an endogenous noise-cancelling system. This highlights the importance of psychotherapeutic treatment approaches for chronic tinnitus.