Auditory scene analysis and attentional focusing in speech perception under complex dynamic listening conditions in younger and older adults

在不利的（鸡尾酒会）听力条件下的言语理解随着年龄的增长而恶化。据推测，除了真正的听力缺陷外，与年龄相关的认知能力下降也导致了这些困难。在项目的第一阶段，我们证明了注意力和抑制控制的下降会影响语音感知，特别是在高度动态的听觉场景和说话人发生变化后。观察到的行为表现缺陷与电生理测量的年龄相关变化有关，反映了老年人注意力分散的增加，注意力分配的灵活性降低，以及相关言语信息处理的准备减少。然而，先前的研究也表明，老年人从暗示听觉环境和说话人环境变化的线索中获益的程度与年轻人相似。一种非常自然的线索是说话者面部提供的视觉语音信息。人们早就知道，视觉语言可以大大提高（听觉）语言的理解能力。这种双峰视听促进是基于这样一个事实，即视觉言语对听觉话语具有特定的预测价值。听觉和视觉语音信息的整合减少了信号的不确定性，并支持相关语音信息的提取，特别是在不利的听力条件下。有趣的是，事件相关电位（ERPs）分析显示，老年人从双峰语音信息中获益比年轻人更多。在高度动态的鸡尾酒会上，视听语音信息能在多大程度上提高语音理解能力尚不清楚。然而，根据我们之前的研究结果，我们可以预期，当听觉环境和说话人环境发生变化时，视觉语音也会对语音理解产生积极的影响。在项目的第二阶段，这应该在四个实验中进行调查，使用真实的听力场景，并结合行为和电生理测量。通过将听觉言语与(a)一致的视觉言语，(b)产生非（言语）特定嘴唇运动的面孔，以及(c)静态面孔相结合，应该在年轻人和老年人中测试动态听力条件下AV言语的具体益处。实验的重点是改变说话人的设置，以及与变化相关的注意力转换相关的转换成本。潜在的皮质过程将被ERP方法分析。在这里，分析将集中在项目第一阶段被证明对说话人变化（N400diff和LPCdiff）、注意转换（N2ac和LPCpc）和年龄（N2和CNV）敏感的erp上。综上所述，新实验的目的是进一步了解视听语音加工的神经生理机制及其与不利听力条件下语音理解的关系。

Speech comprehension under adverse (cocktailparty) listening conditions deteriorates with age. It is assumed that, in addition to genuine hearing deficits, age-related declines in cognitive abilities contribute to these difficulties. In the first phase of the project, we demonstrated that declines in attentional and inhibitory control affect speech perception especially in highly dynamic auditory sceneries and after the occurrence of speaker changes. Deficits observed in behavioural performance were associated with age-related changes in electrophysiological measures, reflecting increased distraction, less flexible attention allocation, and reduced preparation of the processing of relevant speech information in older adults. However, previous studies also showed that older adults benefit from cues indicating changes in the auditory scenery and in speaker settings to a similar degree as younger adults. A quite natural type of cue is visual speech information provided by the speakers face. It is long known that visual speech can substantially improve (auditory) speech comprehension. This bimodal audio-visual (AV) facilitation is based on the fact that visual speech carries a specific predictive value for the auditory utterance. The integration of auditory and visual speech information reduces signal uncertainty and supports the extraction of relevant speech information especially under adverse listening conditions. Interestingly, analyses of eventrelated potentials (ERPs) revealed that older adults benefit even more from bimodal speech information than younger ones. The degree to which audio-visual speech information may enhance speech comprehension also in highly dynamic cocktailparty situations is yet unclear. Regarding our previous results, however, it can be expected that visual speech also has a positive effect on speech comprehension when changes in the auditory scenery and in speaker settings occur. In the second phase of the project, this should be investigated in four experiments, using realistic listening scenarios and combined behavioural and electro-physiological measures. By combining auditory speech with (a) congruent visual speech, (b) faces that produce non(speech)specific lip movements, and (c) static faces, the specific benefits of AV speech under dynamic listening conditions should be tested in younger and older adults. The experiments focus on changing speaker settings and on switch costs associated with change-related attentional switching. The underlying cortical processes will be analysed by ERP methodology. Here, the analysis will focus on ERPs that proved to be sensitive to speaker changes (N400diff und LPCdiff), to attentional switching (N2ac and LPCpc), and to age (N2 and CNV) in the first phase of the project. In sum, the aim of the new experiments is to learn more about the neurophysiological mechanisms of audio-visual speech processing and their relation to benefits in speech comprehension under adverse listening.