Gabor Frame Phase Stability Analysis of Chirp Evoked Auditory Brainstem Responses

We have shown that click evoked auditory brainstem response (ABR) single sweeps can be efficiently processed using a novelty detection paradigm. In this paradigm, the diagnostic system is self-adjusted to the individual measurement setting using the spontaneous activity. ABRs as a large-scale reflection of a stimulus locked neuronal group synchronization at the brainstem level are detected as novel instance - novel as compared to the spontaneous activity which does not exhibit a regular stimulus locked synchronization. In this paper we propose for the first time Gabor frame operators as an efficient feature extraction technique for ABR single sweeps. In particular, we use this decomposition technique to derive the Gabor frame phase stability (GFPS) of sweep sequences of click and chirp evoked ABRs. We show that the GFPS represents a robust feature of ABRs and that GFPS of chirp evoked ABRs provides a stable discrimination of the spontaneous activity from stimulations above the hearing threshold with a minimum number of sweeps, even at low stimulation intensities. This is the first study that is directed to a single sweep analysis of chirp evoked ABRs. We conclude that our study reinforces the use of chirp stimulations for the fast hearing threshold detection. The presented method might be used in expert based diagnostic procedures directly or for the ultra-fast detection of the hearing threshold by cojoint systems with a computational decision making stage according to the novelty detection paradigm.