Auditory steady-state responses and clinical applications.

The auditory steady-state responses to single continuous tones modulated in amplitude have been proposed as an alternative to objective frequency-specific audiometry. The aim of this study was to compare thresholds obtained by pure-tone audiometry (PTA) and by auditory steady-state responses in normal hearing or affected by hearing loss in adults and in order to evaluate the applicability of this objective test in no collaborative hearing-impaired subjects. Eleven people, 6 normal hearing and 5 with hearing loss, underwent PTA and multiple frequency auditory steady-state responses; simultaneous carrier tones (0.5, 1, 2 and 4 KHz) modulated in amplitude at different rates (77-105 Hz) were presented monaurally (TDH 49 earphones) at variable intensities (110-20 dB SPL). The mean threshold difference between PTA and multiple frequency auditory steady-state responses was 28 dB (standard deviation=14.2) and R correlation value at 0.5-1-2-4 kHz was 0.71 (P=0.0012) at the Pearson's test. These differences were significantly smaller considering the hearing-impaired separately (11.7 dB, standard deviation=2.9). The results of this study confirm previous reports showing that the multiple auditory steady-state response method is an accurate predictor of the behavioural audiogram in patients with sensory-neural hearing impairments and can be used as a valid support for behavioural evaluations.