EEG Alpha Activity as a Candidate Neural Marker of Listening Effort During Speech-In-Noise Perception in Cochlear Implant Users

BACKGROUND

Cochlear implant (CI) users commonly report that a high degree of listening effort (LE) is required to overcome difficulty with understanding speech in challenging environments, such as in noise or with competing talkers. Over time, high LE can lead to exhaustion and sometimes discontinued CI use. The physiological processes underlying LE are not well understood, making it difficult to target these mechanisms to assist with rehabilitation. Our past research in both normal-hearing (NH) and CI users has however found that inter-individual differences in frontal alpha oscillations (8-12 Hz) in the EEG correlate with self-reported LE in a speech-in-noise perception task, suggesting this activity is a candidate neural marker of LE.

OBJECTIVE

In contrast to inter-individual differences, the goal of the current study is to determine if intra-individual changes in alpha activity can explain different degrees of LE exerted by the same CI user.

METHODS

In an 8-speaker free field, adult CI users (N = 7) were presented three spoken digits in multi-talker babble noise at different signal-to-noise ratios. After each trial (180 total), CI users reported the digits that they heard, and rated LE on a 1-10 scale. During this time the 64-channel EEG was recorded.

RESULTS

LE ratings significantly correlated to single-trial alpha power in right frontal brain regions in all CI users, consistent with networks associated with attention and speech comprehension.

CONCLUSIONS

Results suggest that alpha activity indexes self-reported listening effort and can be used as an objective neural marker in CI users.

Funded by MED-EL