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Comparison of electrically evoked compound action potential thresholds and loudness estimates for the stimuli used to program the Advanced Bionics cochlear implant
Journal article   Peer reviewed

Comparison of electrically evoked compound action potential thresholds and loudness estimates for the stimuli used to program the Advanced Bionics cochlear implant

Eun Kyung Jeon, Carolyn J Brown, Christine P Etler, Sara O'Brien, Li-Kuei Chiou and Paul J Abbas
Journal of the American Academy of Audiology, Vol.21(1), pp.16-27
01/2010
DOI: 10.3766/jaaa.21.1.3
PMCID: PMC2875933
PMID: 20085196

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Abstract

In the mid-1990s, Cochlear Corporation introduced a cochlear implant (CI) to the market that was equipped with hardware that made it possible to record electrically evoked compound action potentials (ECAPs) from CI users of all ages. Over the course of the next decade, many studies were published that compared ECAP thresholds with levels used to program the speech processor of the Nucleus CI. In 2001 Advanced Bionics Corporation introduced the Clarion CII cochlear implant (the Clarion CII internal device is also known as the CII Bionic Ear). This cochlear implant was also equipped with a system that allowed measurement of the ECAP. While a great deal is known about how ECAP thresholds compare with the levels used to program the speech processor of the Nucleus CI, relatively few studies have reported comparisons between ECAP thresholds and the levels used to program the speech processor of the Advanced Bionics CI. To explore the relationship between ECAP thresholds and behavioral measures of perceptual dynamic range for the range of stimuli commonly used to program the speech processor of the Advanced Bionics CI. This prospective and experimental study uses correlational and descriptive statistics to define the relationship between ECAP thresholds and perceptual dynamic range measures. Twelve postlingually deafened adults participated in this study. All were experienced users of the Advanced Bionics CI system. ECAP thresholds were recorded using the commercially available SoundWave software. Perceptual measures of threshold (T-level), most comfortable level (M-level), and maximum comfortable level (C-level) were obtained using both "tone bursts" and "speech bursts." The relationship between these perceptual and electrophysiological variables was defined using paired t-tests as well as correlation and linear regression. ECAP thresholds were significantly correlated with the perceptual dynamic range measures studied; however, correlations were not strong. Analysis of the individual data revealed considerable discrepancy between the contour of ECAP threshold versus electrode function and the behavioral loudness estimates used for programming. ECAP thresholds recorded from Advanced Bionics cochlear implant users always indicated levels where the programming stimulus was audible for the listener. However, the correlation between ECAP thresholds and M-levels (the primary metric used to program the speech processor of the Advanced Bionics CI), while statistically significant, was quite modest. If programming levels are to be determined on the basis of ECAP thresholds, care should be taken to ensure that stimulation is not uncomfortably loud, particularly on the basal electrodes in the array.
 User-Computer Interface Loudness Perception - physiology Telemetry - methods Humans Middle Aged Deafness - physiopathology Male Prosthesis Design Acoustic Stimulation - methods Evoked Potentials, Auditory - physiology Aged, 80 and over Auditory Threshold - physiology Adult Female Aged Cochlear Implants Deafness - rehabilitation

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