This study aimed to (1) determine the sensitivity of the electrically evoked auditory change complex (eACC) to changes in stimulating electrode position; and (2) investigate the association between results of eACC measures and behavioral electrode discrimination and their association with speech-perception performance in pediatric cochlear implant (CI) users who have auditory neuropathy spectrum disorder (ANSD).
Fifteen children with ANSD ranging in age between 5.4 and 18.6 years participated in this study. All subjects used Cochlear Nucleus devices. For each subject, open-set speech-perception ability was assessed using the Phonetically Balanced Kindergarten word lists presented at 60 dB SPL, using monitored live voice in a sound booth. Behavioral and objective measures of electrode discrimination were assessed in a nonclinical test environment. The stimuli used to elicit these measures were 800 msec biphasic pulse trains delivered by a direct interface to the CI. Data were collected from two basic stimulation conditions. In the standard condition, the entire pulse train was delivered to a mid-array electrode (electrode 11 or 12) at the maximum comfortable level (C level). In the change condition, the stimulus was split into two 400 msec pulse train segments presented sequentially on two different electrodes. The stimulation level of the second 400 msec pulse train was loudness balanced to the C level of the mid-array electrode used in the standard condition. The separation between the pair of stimulating electrodes was systematically varied. For behavioral electrode-discrimination measures, each subject was required to determine whether he or she heard one or two sounds for stimuli presented in different stimulation conditions. For the eACC measures, two replicates of 100 artifact-free sweeps were recorded for each stimulation condition.
The eACC in response to changes in stimulating electrode position was recorded from all subjects with ANSD using direct electrical stimulation. Electrode-discrimination thresholds determined with the eACC and behavioral measures were consistent. Children with ANSD using CIs who showed poorer speech performance also required larger separations between the stimulating electrode pair to reliably elicit the eACC than subjects with better speech-perception performance. There was a robust correlation between electrode-discrimination capacities and speech-perception performances in subjects tested in this study. The effect of electrode separation on eACC amplitudes was not monotonic.
These results demonstrate the feasibility of using eACC to evaluate electrode-discrimination capacities in children with ANSD. These results suggest that the eACC elicited by changes in stimulating electrode position holds great promise as an objective tool for evaluating spectral-pattern detection in such subjects, which may be predictive of their potential speech-perception performance.
This study aimed to (1) investigate the sensitivity of the electrically evoked auditory change complex (eACC) to changes in stimulating electrode position; and (2) evaluate the relationship between results of eACC measures and behavioral electrode discrimination and their association with speech perception abilities in implanted children with auditory neuropathy spectrum disorder (ANSD). Fifteen implanted children with ANSD who had various speech perception performance participated in this study. Electrode discrimination thresholds measured with eACC recordings and behavioral tasks were consistent. There was a robust correlation between the Phonetically Balanced Kindergarten (PBK) word scores and the electrode discrimination threshold.
Department Otolaryngology—Head and Neck Surgery, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
This work was supported by grants from the National Institutes of Health/National Institute on Deafness and Other Communication Disorders (1R21DC011383) and Deafness Research Foundation.
Portions of this article were presented at the Objective Measures in Auditory Implants—7th International Symposium, Amsterdam, The Netherlands, in 2012.
Dr. Craig A. Buchman is a member of Cochlear Corp. Surgeon’s Advisory Board and Dr. Holly F. B. Teagle is a member of a Cochlear Corp. Audiology Advisory Board.
The authors declare no other conflict of interest.
Address for correspondence: Shuman He, G190 Physicians Office Building, 170 Manning Drive, Department of Otolaryngology—Head and Neck Surgery, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA. E-mail: email@example.com