ENT/Audiology and the EMGO+ Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands.
Ear Hear. 2011 Jul-Aug;32(4):498-510. doi: 10.1097/AUD.0b013e31820512bb.
The aim of the present study was to evaluate the influence of age, hearing loss, and cognitive ability on the cognitive processing load during listening to speech presented in noise. Cognitive load was assessed by means of pupillometry (i.e., examination of pupil dilation), supplemented with subjective ratings.
Two groups of subjects participated: 38 middle-aged participants (mean age = 55 yrs) with normal hearing and 36 middle-aged participants (mean age = 61 yrs) with hearing loss. Using three Speech Reception Threshold (SRT) in stationary noise tests, we estimated the speech-to-noise ratios (SNRs) required for the correct repetition of 50%, 71%, or 84% of the sentences (SRT50%, SRT71%, and SRT84%, respectively). We examined the pupil response during listening: the peak amplitude, the peak latency, the mean dilation, and the pupil response duration. For each condition, participants rated the experienced listening effort and estimated their performance level. Participants also performed the Text Reception Threshold (TRT) test, a test of processing speed, and a word vocabulary test. Data were compared with previously published data from young participants with normal hearing.
Hearing loss was related to relatively poor SRTs, and higher speech intelligibility was associated with lower effort and higher performance ratings. For listeners with normal hearing, increasing age was associated with poorer TRTs and slower processing speed but with larger word vocabulary. A multivariate repeated-measures analysis of variance indicated main effects of group and SNR and an interaction effect between these factors on the pupil response. The peak latency was relatively short and the mean dilation was relatively small at low intelligibility levels for the middle-aged groups, whereas the reverse was observed for high intelligibility levels. The decrease in the pupil response as a function of increasing SNR was relatively small for the listeners with hearing loss. Spearman correlation coefficients indicated that the cognitive load was larger in listeners with better TRT performances as reflected by a longer peak latency (normal-hearing participants, SRT50% condition) and a larger peak amplitude and longer response duration (hearing-impaired participants, SRT50% and SRT84% conditions). Also, a larger word vocabulary was related to longer response duration in the SRT84% condition for the participants with normal hearing.
The pupil response systematically increased with decreasing speech intelligibility. Ageing and hearing loss were related to less release from effort when increasing the intelligibility of speech in noise. In difficult listening conditions, these factors may induce cognitive overload relatively early or they may be associated with relatively shallow speech processing. More research is needed to elucidate the underlying mechanisms explaining these results. Better TRTs and larger word vocabulary were related to higher mental processing load across speech intelligibility levels. This indicates that utilizing linguistic ability to improve speech perception is associated with increased listening load.
本研究旨在评估年龄、听力损失和认知能力对噪声环境下言语聆听时认知处理负荷的影响。通过瞳孔测量（即瞳孔扩张检查）来评估认知负荷，并辅以主观评分。
本研究纳入了两组受试者：38 名中年听力正常受试者（平均年龄=55 岁）和 36 名中年听力损失受试者（平均年龄=61 岁）。使用三个语音接受阈（SRT）在固定噪声测试中，我们估计了正确重复 50%、71%或 84%句子所需的言语-噪声比（SNR）（分别为 SRT50%、SRT71%和 SRT84%）。我们在聆听过程中检查了瞳孔反应：峰值振幅、峰值潜伏期、平均扩张和瞳孔反应持续时间。对于每种情况，参与者都对所经历的聆听努力进行了评分，并估计了他们的表现水平。参与者还进行了文本接受阈（TRT）测试，这是一个处理速度测试，以及词汇测试。将数据与之前发表的正常听力的年轻参与者的数据进行了比较。
听力损失与相对较差的 SRT 相关，较高的言语可懂度与较低的努力和较高的表现评分相关。对于听力正常的受试者，年龄的增加与 TRT 较差和处理速度较慢相关，但词汇量较大。多变量重复测量方差分析表明，组和 SNR 有主要影响，并且这些因素之间存在交互作用，对瞳孔反应有影响。对于中年组，在低可懂度水平下，潜伏期相对较短，平均扩张相对较小，而在高可懂度水平下则相反。对于听力损失的受试者，随着 SNR 的增加，瞳孔反应的减少相对较小。Spearman 相关系数表明，对于 TRT 表现较好的受试者，认知负荷较大，表现为更长的峰值潜伏期（正常听力受试者，SRT50%条件）和更大的峰值振幅和更长的反应持续时间（听力受损受试者，SRT50%和 SRT84%条件）。此外，对于听力正常的受试者，在 SRT84%条件下，较大的词汇量与较长的反应持续时间相关。
瞳孔反应随着言语可懂度的降低而系统地增加。年龄增长和听力损失与增加噪声环境下言语的可懂度时释放的努力减少有关。在困难的聆听条件下，这些因素可能会相对较早地引起认知过载，或者与较浅的言语处理有关。需要进一步的研究来阐明解释这些结果的潜在机制。更好的 TRT 和更大的词汇量与言语可懂度水平上的更高的心理处理负荷相关。这表明，利用语言能力来改善言语感知与增加聆听负荷有关。
