Ten(HL)-test results and psychophysical tuning curves for subjects with auditory neuropathy

Auditory neuropathy is a hearing disorder characterized by abnormal or absent auditory brainstem responses, and the presence of otoacoustic emissions and/or cochlear microphonics, indicating normal functioning of the outer hair cells. Here, subjects with auditory neuropathy, with near-normal hearing to moderate hearing loss, were tested using the TEN(HL) test for diagnosis of dead regions and also using psychophysical tuning curves (PTCs). Results for the majority of subjects met the TEN(HL)-test criteria at one or more frequencies (often at several or all frequencies). However, the PTCs did not show shifted tips. Hence, the positive results of the TEN(HL) test should not be interpreted as indicating the presence of dead regions. Rather, it appears that high thresholds in noise are caused by poor processing efficiency, perhaps associated with loss of neural synchrony.