Neubert Christiane R, Förstel Alexander P, Debener Stefan, Bendixen Alexandra
Cognitive Systems Lab, Faculty of Natural Sciences, Institute of Physics, Chemnitz University of Technology, Chemnitz, Germany.
Neuropsychology Lab, Department of Psychology, Carl von Ossietzky University of Oldenburg, Oldenburg, Germany.
Front Hum Neurosci. 2021 Oct 29;15:734231. doi: 10.3389/fnhum.2021.734231. eCollection 2021.
When multiple sound sources are present at the same time, auditory perception is often challenged with disentangling the resulting mixture and focusing attention on the target source. It has been repeatedly demonstrated that background (distractor) sound sources are easier to ignore when their spectrotemporal signature is predictable. Prior evidence suggests that this ability to exploit predictability for foreground-background segregation degrades with age. On a theoretical level, this has been related with an impairment in elderly adults' capabilities to detect certain types of sensory deviance in unattended sound sequences. Yet the link between those two capacities, deviance detection and predictability-based sound source segregation, has not been empirically demonstrated. Here we report on a combined behavioral-EEG study investigating the ability of elderly listeners (60-75 years of age) to use predictability as a cue for sound source segregation, as well as their sensory deviance detection capacities. Listeners performed a detection task on a target stream that can only be solved when a concurrent distractor stream is successfully ignored. We contrast two conditions whose distractor streams differ in their predictability. The ability to benefit from predictability was operationalized as performance difference between the two conditions. Results show that elderly listeners can use predictability for sound source segregation at group level, yet with a high degree of inter-individual variation in this ability. In a further, passive-listening control condition, we measured correlates of deviance detection in the event-related brain potential (ERP) elicited by occasional deviations from the same spectrotemporal pattern as used for the predictable distractor sequence during the behavioral task. ERP results confirmed neural signatures of deviance detection in terms of mismatch negativity (MMN) at group level. Correlation analyses at single-subject level provide no evidence for the hypothesis that deviance detection ability (measured by MMN amplitude) is related to the ability to benefit from predictability for sound source segregation. These results are discussed in the frameworks of sensory deviance detection and predictive coding.
当多个声源同时存在时，听觉感知常常面临如何解析混合声音并将注意力集中在目标声源上的挑战。反复的研究表明，当背景（干扰）声源的频谱-时间特征可预测时，它们更容易被忽略。先前的证据表明，利用可预测性进行前景-背景分离的能力会随着年龄增长而下降。从理论层面来看，这与老年人在未注意的声音序列中检测某些类型感官偏差的能力受损有关。然而，偏差检测和基于可预测性的声源分离这两种能力之间的联系尚未得到实证证明。在此，我们报告一项结合行为学和脑电图（EEG）的研究，该研究调查了老年听众（60 - 75岁）利用可预测性作为声源分离线索的能力以及他们的感官偏差检测能力。听众在一个目标流上执行检测任务，只有当成功忽略同时存在的干扰流时才能完成该任务。我们对比了两种条件，其干扰流在可预测性方面有所不同。从可预测性中获益的能力通过两种条件下的表现差异来衡量。结果表明，老年听众在群体层面上能够利用可预测性进行声源分离，但个体在这种能力上存在高度差异。在另一个被动聆听控制条件下，我们测量了在行为任务期间，与用于可预测干扰序列相同的频谱-时间模式偶尔出现偏差所引发的事件相关脑电位（ERP）中偏差检测的相关指标。ERP结果在群体层面证实了失配负波（MMN）方面的偏差检测神经特征。单受试者层面的相关分析没有为以下假设提供证据：偏差检测能力（通过MMN幅度衡量）与从可预测性中获益进行声源分离的能力相关。我们在感官偏差检测和预测编码的框架下讨论了这些结果。
