Evaluating auditory brainstem response to a level-dependent chirp designed based on derived-band latencies.

The best cochlear-neural delay model for designing a chirp that can produce the largest auditory brainstem response (ABR) has not been established. This study comprised two experiments. Experiment I aimed to estimate the delay model by measuring derived-band ABR latencies at different levels. The results demonstrated that, as the level decreased, the delay between the center frequencies of 0.7 and 5.7 kHz increased. The aim of experiment II was to compare ABRs generated by three stimuli: (1) a level-dependent derived-band (DB)-Chirp, designed based on the model in experiment I; (2) a level-dependent level specific (LS)-Chirp from Kristensen and Elberling [(2012). J. Am. Acad. Audiol. 23, 712-721]; and (3) a click. The results demonstrated that the DB-Chirp produced significantly larger wave V than the LS-Chirp at 45 dB normal hearing level (nHL); however, no differences were observed at other levels. The wave I generated by the DB-Chirp and LS-Chirp were significantly larger than those evoked by the click at 45 and 60 dB nHL and at 30 and 45 dB nHL, respectively; however, at all levels, no differences between these two chirps were observed. The DB-Chirp may be a valuable stimulus for producing ABRs for clinical applications such as assessing cochlear synaptopathy and estimating hearing sensitivity.