Threshold Estimation Using “Chained Stimuli” for Cortical Auditory Evoked Potentials in Individuals With Normal Hearing and Hearing Impairment

Abstract

Purpose We investigated the utility of chained stimuli for threshold estimation using cortical auditory evoked potentials (CAEPs) in individuals with normal hearing sensitivity and hearing loss. The effect of the order of frequency in chained stimuli on CAEPs was also studied. Method Seventeen individuals with normal hearing and 17 individuals with mild to severe sensorineural hearing loss participated in the study. In individuals with normal hearing, CAEPs were recorded at 80 dB nHL for 4 chained stimuli with different orders of frequencies within them (Chained Stimuli 1 [CS1]: 500, 1000, 2000, 4000 Hz; Chained Stimuli 2: 4000, 2000, 1000, 500 Hz; Chained Stimuli 3: 500, 2000, 1000, 4000 Hz; Chained Stimuli 4: 4000, 1000, 2000, 500 Hz). CAEP threshold estimation was carried out using CS1 in both groups and was compared with behavioral pure-tone thresholds. Results CS1 elicited the largest amplitude responses at low and mid frequencies, whereas all 4 stimuli elicited similar amplitude responses at high frequencies. CAEP thresholds were generally within 10–20 dB above the participants' behavioral threshold in both groups. The difference between CAEP threshold and behavioral threshold was less for individuals with hearing loss compared to individuals with normal hearing. There was a significant positive correlation between CAEP threshold and behavioral threshold at all the frequencies. Conclusions CS1 could be used to elicit CAEPs for threshold estimation in adult participants with normal hearing and hearing loss of varied degrees with theoretically reduced testing time. The actual time reduction using chained stimuli and the correction factor to be applied to estimate behavioral threshold can be studied in future investigations.