Use of fNIRS for Objective Programming of Cochlear Implants

Background

A totally objective and reliable method to program a cochlear implant (CI) is crucially needed in the CI clinic, especially for infants. Standard ECAP measures alone have proven inadequate for this purpose, while cortical measures such as cortical auditory evoked potentials show more promise but are inefficient. Our earlier published work with normal-hearing adults showed that hearing thresholds and comfortably-loud levels could be estimated using functional near-infrared spectroscopy (fNIRS) responses.

Objective

In this study we extend this work to develop an objective method to program a CI using fNIRS.

Methods

Adults and children with existing CIs participated and were imaged while listening to tones via direct audio-input into a calibrated research processor to objectively estimate T and C levels. The estimates were compared with the behaviourally-determined T and C levels. fNIRS responses were recorded in the bilateral auditory and pre-frontal cortices.

Results and conclusions

The fNIRS response is easy to measure in CI users and is not subject to electrical artefacts. Preliminary data with CI users are consistent with our earlier work using acoustic stimuli in normal and hearing impaired adults and children, and shows promise for objective programming of CIs.

Acknowledgements

We thank Xin Zhou, Nicola Anglin, Virginia Roncagliolo, and Nicola Horvarth for assistance with recruitment and data collection. CM was supported by Veski and Lions fellowships, HIB by an NHMRC fellowship, and SW by Swiss National Science Foundation (SNSF). The Bionics Institute acknowledges the support it receives from the Victorian Government through its Operational Infrastructure Support Program.