Spectral Integration in Bimodal, Electric-acoustic stimulation (EAS), and Bilateral EAS Technologies
What is it about?
This study explored how effectively acoustic and electric frequency information is integrated (spectral integration) and how frequency spacing influences this integration, across different hearing technologies, including Bimodal, Electric-Acoustic Stimulation (EAS), and Bilateral EAS. It was found that Bilateral EAS achieved the best spectral integration overall. Additionally, both EAS and bimodal hearing demonstrated better integration with narrowly spaced frequency information compared to wider spacings. Notably, within-ear integration in EAS was significantly more effective than across-ear integration in bimodal hearing. Furthermore, bimodal hearing showed a decline in performance or interference when the dominant cue for the /I/ vowel was received by the cochlear implant ear while the non-dominant cue was received by the hearing aid ear.
Why is it important?
Our research demonstrates that combining cochlear implant and hearing aid signals in the same ear (EAS) is more effective and less prone to interference than across-ear combinations (bimodal hearing). For optimal speech perception in EAS, we recommend setting the low-frequency cochlear implant cutoff within 270 Hz of the hearing aid's upper-frequency limit. In bimodal hearing, larger frequency spacings (e.g., 1607 Hz) significantly reduce performance compared to smaller spacings. These findings can guide audiologists in optimizing both EAS and bimodal fittings for patients.