Eccles Institute of Neuroscience, John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia.
Institute of Physiology and Pathology of Hearing, Warsaw, Poland.
Eur J Neurosci. 2021 Apr;53(8):2726-2739. doi: 10.1111/ejn.15122. Epub 2021 Feb 9.
The sensitivity of the auditory system is regulated via two major efferent pathways: the medial olivocochlear system that connects to the outer hair cells, and by the middle ear muscles-the tensor tympani and stapedius. The role of the former system in suppressing otoacoustic emissions has been extensively studied, but that of the complementary network has not. In studies of selective attention, decreases in otoacoustic emissions from contralateral stimulation have been ascribed to the medial olivocochlear system, but the acknowledged problem is that the results can be confounded by parallel muscle activity. Here, the potential role of the muscle system is examined through a wide but not exhaustive review of the selective attention literature, and the unifying hypothesis is made that the prominent "physiological noise" detected in such experiments, which is reduced during attention, is the sound produced by the muscles in proximity to the ear-including the middle ear muscles. All muscles produce low-frequency sound during contraction, but the implications for selective attention experiments-in which muscles near the ear are likely to be active-have not been adequately considered. This review and synthesis suggests that selective attention may reduce physiological noise in the ear canal by reducing the activity of muscles close to the ear. Indeed, such an experiment has already been done, but the significance of its findings have not been widely appreciated. Further sets of experiments are needed in this area.
连接到外毛细胞的内侧橄榄耳蜗系统，以及中耳肌肉——鼓膜张肌和镫骨肌。前者系统在抑制耳声发射中的作用已被广泛研究，但互补网络的作用尚未得到研究。在选择性注意研究中，对侧刺激引起的耳声发射减少归因于内侧橄榄耳蜗系统，但公认的问题是，肌肉活动可能会使结果复杂化。在这里，通过对选择性注意文献的广泛但非详尽的回顾，研究了肌肉系统的潜在作用，并提出了一个统一的假设，即在这些实验中检测到的突出的“生理噪声”（在注意力集中时会减少）是由耳朵附近的肌肉产生的声音，包括中耳肌肉。所有肌肉在收缩时都会产生低频声音，但对于选择性注意实验——其中耳朵附近的肌肉很可能活跃——其影响尚未得到充分考虑。这篇综述和综合研究表明，选择性注意可能通过减少靠近耳朵的肌肉的活动来降低耳道中的生理噪声。事实上，已经进行了这样的实验，但人们对其发现的意义并没有广泛认识。需要在这一领域进行更多的实验。
