Section Audiology, Dept. of Otolaryngology-Head and Neck Surgery and EMGO Institute for Health and Care Research, VU University Medical Center, De Boelelaan 1118, 1081 HZ, Amsterdam, The Netherlands; Department of Behavioural Sciences and Learning, Linnaeus Centre HEAD, The Swedish Institute for Disability Research, Linköping University, SE-581 83 Linköping, Sweden.
Department of Psychology, VU University, Van der Boechorststraat 1, 1081 BT Amsterdam, The Netherlands.
Neuroimage. 2014 Nov 1;101:76-86. doi: 10.1016/j.neuroimage.2014.06.069. Epub 2014 Jul 3.
An important aspect of hearing is the degree to which listeners have to deploy effort to understand speech. One promising measure of listening effort is task-evoked pupil dilation. Here, we use functional magnetic resonance imaging (fMRI) to identify the neural correlates of pupil dilation during comprehension of degraded spoken sentences in 17 normal-hearing listeners. Subjects listened to sentences degraded in three different ways: the target female speech was masked by fluctuating noise, by speech from a single male speaker, or the target speech was noise-vocoded. The degree of degradation was individually adapted such that 50% or 84% of the sentences were intelligible. Control conditions included clear speech in quiet, and silent trials. The peak pupil dilation was larger for the 50% compared to the 84% intelligibility condition, and largest for speech masked by the single-talker masker, followed by speech masked by fluctuating noise, and smallest for noise-vocoded speech. Activation in the bilateral superior temporal gyrus (STG) showed the same pattern, with most extensive activation for speech masked by the single-talker masker. Larger peak pupil dilation was associated with more activation in the bilateral STG, bilateral ventral and dorsal anterior cingulate cortex and several frontal brain areas. A subset of the temporal region sensitive to pupil dilation was also sensitive to speech intelligibility and degradation type. These results show that pupil dilation during speech perception in challenging conditions reflects both auditory and cognitive processes that are recruited to cope with degraded speech and the need to segregate target speech from interfering sounds.
听力的一个重要方面是听众理解言语所需的努力程度。一种有前途的听力努力衡量标准是任务诱发的瞳孔扩张。在这里，我们使用功能磁共振成像（fMRI）来识别 17 名正常听力受试者在理解退化的口语句子时瞳孔扩张的神经相关性。受试者听三种不同方式退化的句子：目标女性语音被波动噪声掩蔽，由单一男性语音掩蔽，或目标语音被噪声编码。根据个人情况调整退化程度，使得 50%或 84%的句子可理解。对照条件包括安静环境下的清晰语音和无声试验。50%可懂度的峰值瞳孔扩张比 84%可懂度大，且最大的是由单一说话人掩蔽的语音，其次是波动噪声掩蔽的语音，最小的是噪声编码的语音。双侧颞上回（STG）的激活也呈现出相同的模式，最广泛的激活是由单一说话人掩蔽的语音。更大的峰值瞳孔扩张与双侧 STG、双侧腹侧和背侧前扣带皮层以及几个额叶脑区的更多激活相关。对瞳孔扩张敏感的颞区的一个子集也对语音可懂度和退化类型敏感。这些结果表明，在具有挑战性的条件下，语音感知期间的瞳孔扩张反映了听觉和认知过程，这些过程被招募来应对退化的语音，并需要将目标语音与干扰声音分离。
