Auditory event related potentials in chronic tinnitus patients with noise induced hearing loss.

In order to explore a possible deficit in auditory central neural activity in tinnitus with noise induced hearing loss (NIHL), auditory event related potentials (ERP) and reaction time (RT) were recorded (measures of central processing) from tinnitus patients (N = 12) and hearing and age matched controls (N = 12). Testing procedure included oddball paradigms and 1 KHz repetitive stimulus, as well as click-induced brainstem auditory evoked potentials (BAEP). ERP amplitudes (waves N1, P2 and P3) in tinnitus patients were significantly lower than in controls in all testing paradigms. No differences were found in ERP peak latencies, BAEP, RT, or response scoring. The lower ERP amplitudes may indicate attenuated or 'abnormal' auditory central processing in NIHL tinnitus patients. It is suggested that this dysfunction reflects an adaptive brain process response to the tinnitus and points to auditory central involvement in tinnitus sensation.