JMIR Publications

ABSTRACT

Background:

Functional near-infrared spectroscopy (fNIRS) studies have demonstrated associations between hearing outcomes after cochlear implantation and plastic brain changes. However, inconsistent results make it difficult to draw conclusions. A major problem is that many variables that need to be controlled. To gain further understanding, a careful preparation and planning of such a functional neuroimaging task is key.

Objective:

Using fNIRS, our main objective is to develop a well-controlled audiovisual speech comprehension task to study brain activation in normal hearing and hearing-impaired individuals (including cochlear implant users). The task should be deductible from clinically established tests, induce maximal cortical activation, use optimal coverage of relevant brain regions, and be reproducible by other research groups.

Methods:

The protocol will consist of a resting state (5 minutes) and two stimulation periods (2x12 minutes). During the stimulation periods, 13 seconds long video-recordings of the clinically established Oldenburg Sentence Test (OLSA) will be presented. Stimuli will be presented in four different modalities: (1) speech in quiet, (2) speech in noise, (3) visual-only (i.e., lip-reading), or (4) audiovisual speech. Each stimulus type will be repeated 10 times in a counter-balanced block design. Interactive question-windows will monitor speech comprehension during the task. After the measurement, we will perform a 3D scan to digitize optode positions and verify the covered anatomical locations.

Results:

This paper reports the study protocol. The Ethics Committee approved the study in January 2021. Enrollment for the study started in August 2021. We expect to publish first results by the end of 2022.

Conclusions:

The proposed audiovisual speech comprehension task will help to understand neural correlates to speech understanding. The comprehensive study will have the potential to provide additional prognostic information, beyond the conventional clinical standards about the underlying plastic brain changes of a hearing-impaired person. It will facilitate more precise indication criteria for cochlear implantation and a better planning of rehabilitation.