Abstract
IntroductionThe performance of auditory steady state response (ASSR) in threshold testing when recorded ipsilaterally and contralaterally, as well as at low and high modulation frequencies (MFs), has not been systematically studied. ObjectiveTo verify the influences of mode of recording (ipsilateral vs. contralateral) and modulation frequency (40Hz vs. 90Hz) on ASSR thresholds. MethodsFifteen female and 14 male subjects (aged 18–30 years) with normal hearing bilaterally were studied. Narrow-band CE-chirp® stimuli (centerd at 500, 1000, 2000, and 4000Hz) modulated at 40 and 90Hz MFs were presented to the participants’ right ear. The ASSR thresholds were then recorded at each test frequency in both ipsilateral and contralateral channels. ResultsDue to pronounced interaction effects between mode of recording and MF (p<0.05 by two-way repeated measures ANOVA), mean ASSR thresholds were then compared among four conditions (ipsi-40Hz, ipsi-90Hz, contra-40Hz, and contra-90Hz) using one-way repeated measures ANOVA. At the 500 and 1000Hz test frequencies, contra-40Hz condition produced the lowest mean ASSR thresholds. In contrast, at high frequencies (2000 and 4000Hz), ipsi-90Hz condition revealed the lowest mean ASSR thresholds. At most test frequencies, contra-90Hz produced the highest mean ASSR thresholds. ConclusionsBased on the findings, the present study recommends two different protocols for an optimum threshold testing with ASSR, at least when testing young adults. This includes the use of contra-40Hz recording mode due to its promising performance in hearing threshold estimation.
Highlights
Auditory steady state response (ASSR) is an electrical potential evoked by periodic amplitude modulated and/or frequency modulated stimuli
At 500 and 1000 Hz test frequencies, the lowest mean ASSR thresholds were noted in contra-40 Hz condition
This is followed by ipsi-40 Hz condition, which showed slightly higher mean ASSR thresholds than that of contra-40 Hz condition (4.2 and 1.4 dB higher at 500 and 1000 Hz, respectively)
Summary
Auditory steady state response (ASSR) is an electrical potential evoked by periodic amplitude modulated and/or frequency modulated stimuli. From conventional auditory evoked potentials, ASSR utilizes an objective threshold detection method, which provides clinicians and researchers a convenient way for estimating behavior hearing thresholds. ASSRs evoked by stimuli at 90 and 40 Hz modulation frequencies (MFs) show consistency with auditory brainstem response (ABR) and activity in the upper region of central auditory nervous system (CANS), respectively.1---4. Similar to ABR, 90 Hz ASSR is the choice for estimating auditory sensitivity at mid and high frequencies. The 40 Hz ASSR, performs like the cortical auditory evoked potential (CAEP), which is suitable for determining auditory sensitivity at low frequencies.[5,6]
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