Abstract
Cochlear implantation is increasingly being used as a hearing-loss treatment for patients with residual hearing in the low acoustic frequencies. These patients obtain combined electric-acoustic stimulation (EAS). Substantial residual hearing and relatively long electrode arrays can lead to interactions between the electric and acoustic stimulation. This work investigated EAS interaction through psychophysical and electrophysiological measures. Moreover, cone-beam computed-tomography data was used to characterize the interaction along spatial cochlear locations. Psychophysical EAS interaction was estimated based on the threshold of audibility of an acoustic probe stimulus in the presence of a simultaneously presented electric masker stimulus. Intracochlear electrocochleography was used to estimate electrophysiological EAS interaction via the telemetry capability of the cochlear implant. EAS interaction was observed using psychophysical and electrophysiological measurements. While psychoacoustic EAS interaction was most pronounced close to the electrical stimulation site, electrophysiological EAS interaction was observed over a wider range of spatial cochlear locations. Psychophysical EAS interaction was significantly larger than electrophysiological EAS interaction for acoustic probes close to the electrode position.
Highlights
Lin et al (2011) investigated electric-on-acoustic and acoustic-on-electric ipsilateral masking using a psychoacoustic experiment
This experiment extends the findings reported in previous studies by Kr€uger et al (2017) and Imsiecke et al (2018), where psychoacoustic electric masking could only be measured toward positive EAFDs
This work shows that cochlear-microphonic potentials (CM)/difference response (DIF) responses derived from intracochlear ECochG recordings can be used to measure electric-acoustic stimulation (EAS) interaction
Summary
Lin et al (2011) investigated electric-on-acoustic and acoustic-on-electric ipsilateral masking using a psychoacoustic experiment. Masking of acoustic responses by electrical stimulation was investigated in a group of six EAS subjects For five of these subjects implanted with a relatively short electrode array (10 mm), no masking due to electrical stimulation was observed. In a single subject implanted with a relatively long electrode array (24 mm), masking of acoustic tones at relatively high acoustic frequencies (500 Hz, 625 Hz, and 750 Hz) was observed when the apical electrodes were simultaneously stimulated. Masking of electrical responses by acoustic stimulation was investigated for two subjects implanted with a 24-mm and with a 10-mm electrode array. The elevation of electrical detection thresholds caused by simultaneously presented acoustic stimulation was observed for apical and middle electrodes independent of the acoustic masker frequency. The masking was characterized as a function of the relative location between the electric and the acoustic
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