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Extending the Limits of Place and Temporal Pitch Perception in Cochlear Implant Users

โœ Scribed by Olivier Macherey; John M. Deeks; Robert P. Carlyon


Book ID
106290612
Publisher
Springer-Verlag
Year
2010
Tongue
English
Weight
576 KB
Volume
12
Category
Article
ISSN
1525-3961

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โœฆ Synopsis


A series of experiments investigated the effects of asymmetric current waveforms on the perception of place and temporal pitch cues. The asymmetric waveforms were trains of pseudomonophasic (PS) pulses consisting of a short, high-amplitude phase followed by a longer (and lower amplitude) opposite-polarity phase. When such pulses were presented in a narrow bipolar (โ€œBP+1โ€) mode and with the first phase anodic relative to the most apical electrode (so-called PSA pulses), pitch was lower than when the first phase was anodic re the more basal electrode. For a pulse rate of 12 pulses per second (pps), pitch was also lower than with standard symmetric biphasic pulses in either monopolar or bipolar mode. This suggests that PSA pulses can extend the range of place-pitch percepts available to cochlear implant listeners by focusing the spread of excitation in a more apical region than common stimulation techniques. Temporal pitch was studied by requiring subjects to pitch-rank single-channel pulse trains with rates ranging from 105 to 1,156ย pps; this task was repeated at several intra-cochlear stimulation sites and using both symmetric and pseudomonophasic pulses. For PSA pulses presented to apical electrodes, the upper limit of temporal pitch was significantly higher than that for all the other conditions, averaging 713ย pps. Measures of discriminability obtained using the method of constant stimuli indicated that this pitch percept was probably weak. However, a multidimensional scaling study showed that the percept associated with a rate change, even at high rates, was orthogonal to that of a place change and therefore reflected a genuine change in the temporal pattern of neural activity.


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Usefulness of auditory evoked potentials
โœ Takeshi Kubo ๐Ÿ“‚ Article ๐Ÿ“… 2004 ๐Ÿ› John Wiley and Sons ๐ŸŒ English โš– 47 KB ๐Ÿ‘ 1 views

## Objective Auditory evoked potential measurements have several advantages in evaluating brain function over other techniques (i.e. functional MRI, PET, MEG). The superior features of evoked potentials are their high temporal resolution, non-invasiveness and ease of handling. We studied auditory