DataSheet1.docx

Current evidence demonstrates that even though some non-native listeners can achieve native-like performance for speech perception tasks in quiet, the presence of a background noise is much more detrimental to speech intelligibility for non-native compared to native listeners. Even when performance is equated across groups, it is likely that greater listening effort is required for non-native listeners. Importantly, the added listening effort might result in increased fatigue and a reduced ability to successfully perform multiple tasks simultaneously. Task-evoked pupil responses have been demonstrated to be a reliable measure of cognitive effort and can be useful in clarifying those aspects. In this study we compared the pupil response for 23 native English speakers and 27 Italian speakers of English as a second language. Speech intelligibility was tested for sentences presented in quiet and in background noise at two performance levels that were matched across groups. Signal-to-noise levels corresponding to these sentence intelligibility levels were pre-determined using an adaptive intelligibility task. Pupil response was significantly greater in non-native compared to native participants across both intelligibility levels. Therefore, for a given intelligibility level, a greater listening effort is required when listening in a second language in order to understand speech in noise. Results also confirmed that pupil response is sensitive to speech intelligibility during language comprehension, in line with previous research. However, contrary to our predictions, pupil response was not differentially modulated by intelligibility levels for native and non-native listeners. The present study corroborates that pupillometry can be deemed as a valid measure to be used in speech perception investigation, because it is sensitive to differences both across participants, such as listener type, and across conditions, such as variations in the level of speech intelligibility. Importantly, pupillometry offers us the possibility to uncover differences in listening effort even when those do not emerge in the performance level of individuals.

当前的研究证据表明，尽管一些非母语听众在安静环境下能够达到母语者水平的语音感知任务表现，但背景噪音对非母语者语音可懂度的损害远大于母语者。即使在两组之间的表现相当的情况下，非母语者可能需要付出更多的听力努力。值得注意的是，这种额外的听力努力可能导致疲劳感加剧，并降低同时成功执行多项任务的能力。研究表明，任务引发的瞳孔反应是衡量认知努力的可靠指标，并且有助于阐明这些方面。在本研究中，我们比较了23名母语英语者和27名以英语为第二语言的意大利语者的瞳孔反应。语音可懂度在安静环境和背景噪音中呈现的句子进行了测试，两组在不同表现水平上进行了匹配。使用自适应可懂度任务预先确定了与这些句子可懂度水平相对应的信噪比。与非母语参与者相比，两组在语音可懂度水平上瞳孔反应均显著增加。因此，对于给定的可懂度水平，在第二语言中为了理解噪音中的语音，需要付出更多的听力努力。结果还证实了瞳孔反应对语言理解过程中的语音可懂度敏感，这与先前的研究一致。然而，与我们的预测相反，瞳孔反应并未因可懂度水平的不同而在母语者和非母语听众之间产生差异调节。当前研究证实，瞳孔测量法可以被视为语音感知研究中有效的测量手段，因为它对参与者间的差异（如听众类型）和条件间的差异（如语音可懂度水平的变化）均敏感。重要的是，瞳孔测量法为我们提供了揭示听力努力差异的可能性，即使这些差异并未在个人表现水平上显现。