Application of chirp stimuli in Kalman-weighted auditory brainstem response testing

Objective The Vivosonic Integrity auditory brainstem response (ABR) system, featuring the Kalman-weighted averaging algorithm, was designed for awake testing in infants and young children. Despite reducing noise and state dependency, previous research has indicated that testing conditions still significantly affect ABR thresholds. Compared with the click stimulus most commonly used in clinical ABR testing, chirp stimuli compensate for the temporal dispersion occurring in the cochlea and overcome the traveling wave delay caused by the special anatomical structure of the cochlea. They enable more nerve fibers to discharge synchronously, thereby generating a stronger evoked waveform, which in turn enhances the anti-interference capability of ABR testing. The present study aimed to explore the application of chirp stimuli in Kalman-weighted averaging ABR and to optimize solutions for obtaining objective hearing results in nonsedated states. Methods Twenty-four adults (48 ears) with normal hearing aged 18–34 were enrolled for ABR testing using the Vivosonic Integrity system in three states: lying, sitting, and writing, which simulate the states of young children most commonly encountered during nonsedated ABR testing. Chirp/narrowband-chirp (NB-chirp) ABR thresholds and acquisition durations were recorded and compared with previous results of click ABR (cABR)/tone-burst ABR (tbABR) with Kalman-weighted averaging. Results (1) The thresholds and acquisition time of the chirp/NB-chirp ABR increased significantly generally in the order: lying < sitting < writing. (2) Chirp/NB-chirp ABR showed less variance across states, closer responses to the hearing threshold, and shorter testing durations than cABR/tbABR. Conclusions Chirp/NB-chirp ABR with the Kalman-weighted averaging algorithm demonstrated better noise resistance and shorter testing time than cABR/tbABR. These stimuli together with Kalman-weighted averaging provide advantages for threshold measurement in awake subjects, but it still requires respective normal and correction values for each testing state.