Effect of audiometric configuration on threshold and suprathreshold auditory steady-state responses

The auditory steady-state response (ASSR) has been suggested as an alternative evoked potential for frequency-specific estimation of the behavioral audiogram. Although ASSR thresholds have generally been shown to correlate well with behavioral thresholds, little research has focused on the accuracy of these estimations for specific audiometric configurations. In addition, the form and clinical utility of suprathreshold ASSR measures in individuals with different audiometric configurations has not been examined.; This study examined ASSR measures in subjects with two common audiometric configurations. It was hypothesized that the correlation between ASSR and behavioral thresholds would depend on audiometric configuration. A second hypothesis was that the slope of the suprathreshold ASSR growth function would depend on the presence of hearing loss and on audiometric configuration. Finally, since suprathreshold responses may be larger and more stable than threshold measures, it was hypothesized that behavioral thresholds could be accurately estimated using suprathreshold ASSR measures.; ASSR thresholds and suprathreshold measures were obtained from 10 normal-hearing subjects, 10 subjects with sloping audiometric configurations, and 10 subjects with flat audiometric configurations. ASSR and behavioral thresholds were found to be strongly correlated. Slightly poorer correlations were obtained in the normal-hearing subjects than in hearing-impaired subjects, and for the 500 Hz test frequency compared to the higher frequencies. Correction and regression methods for predicting behavioral thresholds from ASSR thresholds were found to be equally accurate.; Suprathreshold amplitude growth was variable among individuals, but mean growth functions showed steeper slopes in hearing-impaired subjects than in normal hearing subjects, particularly for the higher frequencies (2000–4000 Hz). There was not a significant difference in growth function slope between sloping and flat audiometric configurations for these frequencies. This result, along with the accuracy of threshold estimation for either audiometric configuration, suggests that there is little spread of activation to neighboring regions of the cochlea when using multiple 100% AM stimuli in subjects with moderately sloping losses. Estimation of threshold from suprathreshold ASSR amplitude growth functions proved to be variable, with the exception of the results for the 2000 Hz test frequency.