Characterization of cochlear implant-related artifacts during sound-field recording of the auditory steady state response using an amplitude modulated stimulus: A comparison among normal hearing adults, cochlear implant recipients, and implant-in-a-box

Abstract

Recent work has investigated the use of electric stimuli to evoke auditory steady state response (ASSR) in cochlear implant (CI) users. While more control can be exerted using electric stimuli, acoustic stimuli present natural listening environment for CI users. However, ASSR using acoustic stimuli in the presence of a CI could lead to artifacts. Five experiments investigated the presence and characteristics of CI-artifacts during sound-field ASSR using amplitude modulated (AM) stimulus (carrier frequency: 2 kHz; modulation frequency: 82.031 Hz). Experiment 1 investigated differences between 10 normal hearing (NH) and 10 CI participants in terms of ASSR amplitude versus intensity and onset phase versus intensity. Experiment 2 explored similar relationships for an implant-in-a-box. Experiment 3 investigated correlations between electrophysiological ASSR thresholds (ASSRe) and behavioral thresholds to the AM stimulus (BTAM) for the NH and CI groups. Mean threshold differences (ASSRe-BTAM) were computed for each group and group differences were studied. Experiment 4 investigated the presence of transducer-related artifacts using masking. Experiment 5 investigated the effect of manipulation of intensity and external components of the CI on the ASSR. Overall, results of this study provide the first comprehensive description of the characteristics of CI-artifacts during sound-field ASSR. Implications for future research to further characterize CI-artifacts, thereby leading to strategies to minimize them are discussed.