Department of Communication Sciences and Disorders, Syracuse University, NY.
Geisel School of Medicine, Dartmouth, Hanover College, NH.
J Speech Lang Hear Res. 2021 Oct 4;64(10):4014-4029. doi: 10.1044/2021_JSLHR-21-00048. Epub 2021 Aug 31.
Purpose Background noise has been categorized as energetic masking due to spectrotemporal overlap of the target and masker on the auditory periphery or informational masking due to cognitive-level interference from relevant content such as speech. The effects of masking on cortical and sensory auditory processing can be objectively studied with the cortical auditory evoked potential (CAEP). However, whether effects on neural response morphology are due to energetic spectrotemporal differences or informational content is not fully understood. The current multi-experiment series was designed to assess the effects of speech versus nonspeech maskers on the neural encoding of speech information in the central auditory system, specifically in terms of the effects of speech babble noise maskers varying by talker number. Method CAEPs were recorded from normal-hearing young adults in response to speech syllables in the presence of energetic maskers (white or speech-shaped noise) and varying amounts of informational maskers (speech babble maskers). The primary manipulation of informational masking was the number of talkers in speech babble, and results on CAEPs were compared to those of nonspeech maskers with different temporal and spectral characteristics. Results Even when nonspeech noise maskers were spectrally shaped and temporally modulated to speech babble maskers, notable changes in the typical morphology of the CAEP in response to speech stimuli were identified in the presence of primarily energetic maskers and speech babble maskers with varying numbers of talkers. Conclusions While differences in CAEP outcomes did not reach significance by number of talkers, neural components were significantly affected by speech babble maskers compared to nonspeech maskers. These results suggest an informational masking influence on neural encoding of speech information at the sensory cortical level of auditory processing, even without active participation on the part of the listener.
目的
背景噪声可分为能量掩蔽，这是由于目标和掩蔽声在听觉外周的频谱和时程重叠所致，或信息掩蔽，这是由于与言语等相关内容的认知水平干扰所致。掩蔽对皮质和感觉听觉处理的影响可以用皮质听觉诱发电位（CAEP）来客观研究。然而，神经反应形态的变化是否是由于能量频谱和时程差异或信息内容引起的，尚不完全清楚。本系列多实验旨在评估言语与非言语掩蔽器对中枢听觉系统中言语信息的神经编码的影响，特别是在言语噪声掩蔽器的说话人数量变化方面。
方法
正常听力的年轻人对言语音节做出反应，同时记录皮质听觉诱发电位（CAEP），在存在能量掩蔽器（白噪声或言语噪声）和不同量的信息掩蔽器（言语噪声掩蔽器）的情况下。信息掩蔽的主要操作是言语噪声掩蔽器中的说话人数，将 CAEP 的结果与具有不同时间和频谱特征的非言语噪声掩蔽器进行比较。
结果
即使当非言语噪声掩蔽器在频谱上被塑形并在时间上调制为言语噪声掩蔽器时，在主要的能量掩蔽器和具有不同说话人数的言语噪声掩蔽器存在的情况下，对言语刺激的 CAEP 的典型形态也会发生明显变化。
结论
虽然 CAEP 结果的差异在说话人数上没有达到显著水平，但与非言语掩蔽器相比，言语噪声掩蔽器对神经成分的影响显著。这些结果表明，即使在听众没有主动参与的情况下，信息掩蔽也会对感觉皮质水平的听觉处理中的言语信息编码产生影响。
