Luminance effects on pupil dilation in speech-in-noise recognition

Area of Science:

• Audiology and Speech Communication
• Psychology
• Neuroscience

Background:

• Assessing listening effort is crucial for audiology, especially for hearing loss populations.
• Pupillometry shows promise for measuring listening effort, but methodological challenges remain.
• The impact of varying light conditions on pupillometry for listening effort is not well understood.

Purpose of the Study:

• To investigate the robustness of pupillometry measures of listening effort under different luminance conditions.
• To determine how changes in background light affect pupil dynamics during speech comprehension in noise.

Main Methods:

• Two experiments were conducted using sentences presented at various signal-to-noise ratios (SNRs).
• Pupil dynamics, specifically peak pupil dilation (PPD), were measured.
• Experiment 2 systematically varied luminance levels (0, 75, 220 lux) at two SNRs (0 and +14 dB).

Main Results:

• Peak pupil dilation (PPD) increased at lower SNRs and with sentence misunderstanding, replicating previous findings.
• The effect of SNR on PPD was non-monotonic with changes in luminance.
• Pupillometry metrics for listening effort were sub-optimal in both very dark and very bright conditions.

Conclusions:

• Current pupillometry methods for assessing listening effort are not robust to variations in background luminance.
• Deriving reliable pupillary metrics requires careful consideration of lighting conditions.
• These findings pose constraints for the real-world application of pupillometry in audiology and clinical settings.