Objectives: To evaluate the accuracy with which the innovative QASSR method predicts behavioral thresholds in adult patients with sensorineural hearing loss.
Design: Subjects were tested at four carrier frequencies (500, 1000, 2000, and 4000 Hz).The resulting QASSR recordings were analyzed for thresholds and magnitude/phase characteristics. Tone-burst ABR was recovered from QASSR signal using CLAD method and analyzed in the time domain. The electrophysiological estimates were compared to hearing thresholds determined behaviorally.
Study sample: Sixteen ears of nine volunteer subjects recruited from a clinical population.
Results: All mean threshold estimates differed less than 3 dB for QASSR and less than 5 dB for ABR at 1000, 2000 and 4000Hz (carrier or pure-tone test frequencies). The largest differences were observed for both at 500 Hz (5.63 and 11.56 dB respectively).The audiometric configurations of QASSR and ABR estimates followed those of the respective behaviorally determined configurations across ears tested.
Conclusions: QASSR method merges two dissimilar stimulation techniques, transient and steady-state, to create a hybrid stimulation-and-analysis paradigm that seems to improve the overall performance of the electrophysiological threshold estimation. The unique feature of the QASSR technique is the additional information afforded by the transient ABR, recovered from the same recording. The QASSR thus holds promise to be a very useful tool for practical clinical applications.
Keywords: Auditory steady-state response; auditory brainstem response; auditory evoked potential; continuous loop averaging deconvolution; hearing loss; hearing threshold; visual detection level.