Department of Communication Sciences and Disorders, University of Haifa, Haifa, Israel.
PLoS One. 2022 Feb 23;17(2):e0264282. doi: 10.1371/journal.pone.0264282. eCollection 2022.
The current study characterized subcortical speech sound processing among monolinguals and bilinguals in quiet and challenging listening conditions and examined the relation between subcortical neural processing and perceptual performance. A total of 59 normal-hearing adults, ages 19-35 years, participated in the study: 29 native Hebrew-speaking monolinguals and 30 Arabic-Hebrew-speaking bilinguals. Auditory brainstem responses to speech sounds were collected in a quiet condition and with background noise. The perception of words and sentences in quiet and background noise conditions was also examined to assess perceptual performance and to evaluate the perceptual-physiological relationship. Perceptual performance was tested among bilinguals in both languages (first language (L1-Arabic) and second language (L2-Hebrew)). The outcomes were similar between monolingual and bilingual groups in quiet. Noise, as expected, resulted in deterioration in perceptual and neural responses, which was reflected in lower accuracy in perceptual tasks compared to quiet, and in more prolonged latencies and diminished neural responses. However, a mixed picture was observed among bilinguals in perceptual and physiological outcomes in noise. In the perceptual measures, bilinguals were significantly less accurate than their monolingual counterparts. However, in neural responses, bilinguals demonstrated earlier peak latencies compared to monolinguals. Our results also showed that perceptual performance in noise was related to subcortical resilience to the disruption caused by background noise. Specifically, in noise, increased brainstem resistance (i.e., fewer changes in the fundamental frequency (F0) representations or fewer shifts in the neural timing) was related to better speech perception among bilinguals. Better perception in L1 in noise was correlated with fewer changes in F0 representations, and more accurate perception in L2 was related to minor shifts in auditory neural timing. This study delves into the importance of using neural brainstem responses to speech sounds to differentiate individuals with different language histories and to explain inter-subject variability in bilinguals' perceptual abilities in daily life situations.
本研究在安静和具有挑战性的听力条件下，对单语者和双语者的皮质下言语处理进行了特征描述，并考察了皮质下神经处理与感知表现之间的关系。共有 59 名听力正常的成年人参与了这项研究，年龄在 19 至 35 岁之间，包括 29 名母语为希伯来语的单语者和 30 名阿拉伯语-希伯来语双语者。在安静条件和背景噪声下采集了言语声音的听觉脑干反应。在安静和背景噪声条件下，还评估了言语和句子的感知，以评估感知表现并评估感知-生理关系。在双语者的两种语言（第一语言（L1-阿拉伯语）和第二语言（L2-希伯来语））中测试了感知表现。在安静条件下，单语者和双语者的表现相似。与预期一样，噪声导致感知和神经反应恶化，表现在与安静相比，感知任务的准确性降低，潜伏期延长，神经反应减弱。然而，在噪声中，双语者的感知和生理结果呈现出混合模式。在感知测量中，双语者的准确性明显低于单语者。然而，在神经反应中，双语者的峰潜伏期比单语者更早。我们的研究结果还表明，噪声中的感知表现与皮质下对背景噪声干扰的抵抗力有关。具体来说，在噪声中，脑干阻力增加（即，基频（F0）表示的变化较少或神经时间的变化较小）与双语者更好的言语感知有关。在噪声中，L1 的感知更好与 F0 表示的变化较少有关，而 L2 的感知更准确与听觉神经时间的较小变化有关。本研究深入探讨了使用言语声音的神经脑干反应来区分具有不同语言历史的个体以及解释双语者在日常生活情况下感知能力的个体间变异性的重要性。
