RESUMO
OBJECTIVE: To assess sound field auditory thresholds of hearing-impaired adults by using auditory steady-state evoked responses (ASSRs). DESIGN: ASSRs were recorded to carrier frequencies of 500, 1000, 2000, and 4000 Hz, each uniquely modulated at a single frequency of 80-100 Hz. ASSR thresholds were compared to behavioral auditory thresholds. STUDY SAMPLE: Twenty adults (11 male, age 35.6 years) with moderate-severe sensorineural hearing loss who had used hearing aids, and 10 normal-hearing subjects (mean age 22.4 years). RESULTS: For most frequencies, behavioral sound-field thresholds were slightly lower than ASSR thresholds in both aided and unaided conditions, with a significant correlation between them. Differences between ASSR and behavioral thresholds ranged between 516 dB in the unaided and between 5-16 dB in the aided condition. The ASSR amplitude growth function to 2000 Hz was steeper in both the aided and unaided conditions than in the normal-hearing group. CONCLUSIONS: Sound-field ASSRs can predict behavioral auditory thresholds in both the unaided and aided condition, as well as behavioral functional gains. The ASSR growth function for 2000 Hz is suggested to reflect an underlying mechanism of intensity encoding common to abnormal loudness perception frequently reported in cases of cochlear hearing loss.
