Hearing loss increases firing probability. A, Firing probability plotted against stimulation frequency for CHL (n = 23) and SNHL (n = 23) neurons compared with control neurons (n = 26). Firing probability is the number of action potentials evoked during each stimulation train divided by the number of current pulses. B, Statistical comparison of adjusted firing probability among control, CHL, and SNHL neurons. ANCOVA with stimulation frequency as a covariate, ****p < 0.0001.