Across-site patterns of modulation detection in listeners with cochlear implants.
In modern cochlear implants, much of the information required for recognition of important sounds is conveyed by temporal modulation of the charge per phase in interleaved trains of electrical pulses. In this study, modulation detection thresholds (MDTs) were used to assess listeners' abilities to detect sinusoidal modulation of charge per phase at each available stimulation site in their 22-electrode implants. Fourteen subjects were tested. MDTs were found to be highly variable across stimulation sites in most listeners. The across-site patterns of MDTs differed considerably from subject to subject. The subject-specific patterns of across-site variability of MDTs suggest that peripheral site-specific characteristics, such as electrode placement and the number and condition of surviving neurons, play a primary role in determining modulation sensitivity. Across-site patterns of detection thresholds (T levels), maximum comfortable loudness levels (C levels) and dynamic ranges (DRs) were not consistently correlated with across-site patterns of MDTs within subjects, indicating that the mechanisms underlying across-site variation in these measures differed from those underlying across-site variation in MDTs. MDTs sampled from multiple sites in a listener's electrode array might be useful for diagnosing across-subject differences in speech recognition with cochlear implants and for guiding strategies to improve the individual's perception.
Pfingst
Bryan E
BE
Kresge Hearing Research Institute, Department of Otolaryngology, University of Michigan, Ann Arbor, Michigan 48109-5616, USA. bpfingst@umich.edu
Burkholder-Juhasz
Rose A
RA
Xu
Li
L
Thompson
Catherine S
CS
D000161:Acoustic Stimulation / Q000523:psychology; D000328:Adult; D000368:Aged; D001307:Auditory Perception / Q000502:physiology*; D001309:Auditory Threshold / Q000502:physiology; D003054:Cochlear Implants / Q000523:psychology*; D004558:Electric Stimulation; D004567:Electrodes, Implanted; D004867:Equipment Design; D005260:Female; D006319:Hearing Loss, Sensorineural / Q000503:physiopathology / Q000523:psychology / Q000534:rehabilitation / Q000628:therapy; D006801:Humans; D008297:Male; D008875:Middle Aged; D011571:Psychoacoustics; D013997:Time Factors