Pupillometry and perceived listening effort for cochlear implant users-a comparison of three speech-in-noise tests.

Abstract

Objective: Measuring listening effort using pupillometry is challenging in cochlear implant (CI) users. We assess three validated speech tests (Matrix, LIST, and DIN) to identify the optimal speech material for measuring peak-pupil-dilation (PPD) in CI users as a function of signal-to-noise ratio (SNR).

Design: Speech tests were administered in quiet and two noisy conditions, namely at the speech recognition threshold (0 dB re SRT), i.e. the SNR where speech intelligibility (SI) was 50%, and at a more favourable SNR of +6 dB re SRT. PPDs and subjective ratings of effort were obtained.

Study sample: Eighteen unilaterally implanted CI users.

Results: LIST sentences revealed significantly different PPDs between +6 and 0 dB re SRT and DIN triplets between quiet and +6 dB re SRT. PPDs obtained with the Matrix test were independent of SNR and yielded large PPDs and high subjective ratings even in quiet.

Conclusions: PPD is a sensitive measure for listening effort when processing LIST sentences near 0 dB re SRT and when processing DIN triplets at more favourable listening conditions around +6 dB re SRT. PPDs obtained with the Matrix test were insensitive to SNR, likely because it is demanding for CI users even in quiet.