1. SPATIAL SPREAD MEASUREMENTS
IN HR 90K USERS
Birgit Philips, Paul Corthals, Eddy De Vel, Ingeborg Dhooge
Ghent University, ENT-department, Ghent, Belgium
Background
Ideally, in multi-channel cochlear implants (CI), each electrode should selectively activate a distinct group of neurons in the cochlea.
In reality, the same neurons are stimulated by multiple electrodes because the injected current spreads through the cochlear tissue. If two or more electrodes stimulate overlapping neural populations, whether simultaneously or in sequence, then channel interaction may occur.
Consequently, perception with the CI might be affected.
Objectives
Feasibility of two spatial measurement techniques.
Gaining insight in obtained width values with respect to electrode location (El 3, El 7, El 11) and spatial measurement technique (SOE-VR and SOE-VM).
Evaluating the possible correlations between spatial profiles and speech perception in quiet and noise.
Methods
SOE-Variable Recording
SOE-Variable Masker
RSPOM (research studies platform – objective measures) v.1.3.0
Eight HR 90K adult recipients, Platinum Speech Processor
Three electrode (El) stimulation locations: one apical (El 3), one mid (El 7) and one basal (El 11)
Two spatial measurement techniques: SOE-Variable Recording and SOE-Variable Masker
Symmetric biphasic pulses, pulse width of 32 μs (cathodic pulse first)
Stimuli were given at patient’s Most Comfortable Level
Two-sided exponential decay curve
Width values at 80% of the peak of each fitted curve
Results
Both spatial measurement techniques were found applicable to measure spatial spread within HR 90K users.
A two-way ANOVA revealed a statistical significant main effect for spatial measurement technique (p<.05), but not for electrode location (p>.05).
No significant correlations could be found between spatial measurements and speech perception in quiet nor noise.
Conclusions
Well-known speech materials give no or only restricted frequency-specific information. Possibly, the usage of a detailed phonological test can reveal a correlation with spatial measurements tests.
Musical tuning and melody identification tasks could also be included to gain insight in the relationship between the perception of spectrally rich signals and spatial measurements.