Through the Pupils' Lens: Multilingual Effort in First and Second Language Listening.

Objectives: The present study aimed to examine the involvement of listening effort among multilinguals in their first (L1) and second (L2) languages in quiet and noisy listening conditions and investigate how the presence of a constraining context within sentences influences listening effort.

Design: A group of 46 young adult Arabic (L1)-Hebrew (L2) multilinguals participated in a listening task. This task aimed to assess participants' perceptual performance and the effort they exert (as measured through pupillometry) while listening to single words and sentences presented in their L1 and L2, in quiet and noisy environments (signal to noise ratio = 0 dB).

Results: Listening in quiet was easier than in noise, supported by both perceptual and pupillometry results. Perceptually, multilinguals performed similarly and reached ceiling levels in both languages in quiet. However, under noisy conditions, perceptual accuracy was significantly lower in L2, especially when processing sentences. Critically, pupil dilation was larger and more prolonged when listening to L2 than L1 stimuli. This difference was observed even in the quiet condition. Contextual support resulted in better perceptual performance of high-predictability sentences compared with low-predictability sentences, but only in L1 under noisy conditions. In L2, pupillometry showed increased effort when listening to high-predictability sentences compared with low-predictability sentences, but this increased effort did not lead to better understanding. In fact, in noise, speech perception was lower in high-predictability L2 sentences compared with low-predictability ones.

Conclusions: The findings underscore the importance of examining listening effort in multilingual speech processing and suggest that increased effort may be present in multilingual's L2 within clinical and educational settings.