Stochastic Resonance Based Threshold Improvement in Tinnitus Patients Relies on Phase Locking

Since our 2016 hypothesis on the development of tinnitus by a physiological mechanism to optimize the acoustic information flow into the central auditory system (stochastic resonance, SR), we could find numerous evidences in favor of this mechanism. One of them was based on the audiometric examination of nearly 40,000 patients of our ENT clinic with and without tinnitus, in which we could show that in patients with tinnitus, especially in the range below 3 kHz, which is important for speech understanding, lower hearing thresholds could be observed than in patients without tinnitus. An essential component of our model are so-called delay-lines in the dorsal nucleus cochlearis, which are able to calculate the autocorrelation of the neuronal signal and thus quantify the information content transmitted to the auditory system. This in turn is used to optimize the stochastic resonance and thus the information transmission. Crucial for this information content in the signal is its temporal structure, in the mammal encoded by phase locking up to a maximum frequency of about 5 kHz. With these considerations in mind, we have now re-examined the above data and found that patients with tinnitus below 5 kHz have a significantly better hearing threshold across all frequency ranges than patients with tinnitus above this cutoff frequency. These latter patients even have significantly worse hearing thresholds in the high-frequency range than the patients without tinnitus.