Tone burst stimulus for auditory brainstem responses: prediction of hearing threshold at 1kHz.

Objective: To assess differences in hearing threshold estimation of four different ABR tone-bursts at 1kHz.
Methods: Twenty-one (21) ears from 11 subjects were tested with pure-tone audiometry (PTA): 5 ears (24%) were normal hearing, 5 (24%) affected by mild hearing loss, 7 (33%) showed moderate hearing loss and 4 (19%) severe hearing loss. After PTA each subject underwent tone-burst ABR test at 1kHz using a linear gated (L_ABR) or Blackman windowed (B_ABR) stimuli with (nn_ABR) and without ipsilateral notched noise. Stimulation rate and filters settings were unchanged.
Results: Overall correlation between PTA and all ABRs thresholds was high, ranging from 0.84 to 0.94. In normal hearing ears none of the differences was significant, except for those measured with B&#95;nn&#95;ABR, which showed a mean 16dB overestimation of the pure-tone threshold (p<0.05). In mild hearing loss group none of the differences between thresholds were significant. In moderate and severe hearing loss groups significant differences were measured with L&#95;nn&#95;ABR (p<0.05) with a mean 7.5dB underestimation of PTA.
Conclusions: Although very similar, some significant differences were found when considering specific group of patients with different degrees of hearing loss.
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