Department of Otorhinolaryngology/Head and Neck Surgery, University of Groningen, University Medical Center Groningen, Groningen, Netherlands.
Graduate School of Medical Sciences, Research School of Behavioural and Cognitive Neurosciences, University of Groningen, Groningen, Netherlands.
J Assoc Res Otolaryngol. 2024 Aug;25(4):313-328. doi: 10.1007/s10162-024-00940-7. Epub 2024 May 6.
When David Kemp discovered "spontaneous ear noise" in 1978, it opened up a whole new perspective on how the cochlea works. The continuous tonal sound emerging from most healthy human ears, now called spontaneous otoacoustic emissions or SOAEs, was an unmistakable sign that our hearing organ must be considered an active detector, not just a passive microphone, just as Thomas Gold had speculated some 30 years earlier. Clearly, something is oscillating as a byproduct of that sensitive inbuilt detector, but what exactly is it? Here, we give a chronological account of efforts to model SOAEs as some form of oscillator, and at intervals, we illustrate key concepts with numerical simulations. We find that after many decades there is still no consensus, and the debate extends to whether the oscillator is local, confined to discrete local sources on the basilar membrane, or global, in which an assembly of micro-mechanical elements and basilar membrane sections, coupled by inner ear fluid, interact over a wide region. It is also undecided whether the cochlear oscillator is best described in terms of the well-known Van der Pol oscillator or the less familiar Duffing or Hopf oscillators. We find that irregularities play a key role in generating the emissions. This paper is not a systematic review of SOAEs and their properties but more a historical survey of the way in which various oscillator configurations have been applied to modelling human ears. The conclusion is that the difference between the local and global approaches is not clear-cut, and they are probably not mutually exclusive concepts. Nevertheless, when one sees how closely human SOAEs can be matched to certain arrangements of oscillators, Gold would no doubt say we are on the right track.
1978 年，当大卫·坎普（David Kemp）发现“自发性耳噪声”时，它为耳蜗的工作方式开辟了一个全新的视角。大多数健康人耳中发出的连续音调声，现在称为自发性耳声发射（SOAEs），这是一个确凿的迹象，表明我们的听觉器官必须被视为主动探测器，而不仅仅是被动麦克风，正如托马斯·戈尔德（Thomas Gold）大约 30 年前推测的那样。显然，某种东西在作为内置敏感探测器的副产品而振荡，但具体是什么呢？在这里，我们按时间顺序介绍了将 SOAEs 建模为某种振荡器的努力，并在适当的时候，用数值模拟来说明关键概念。我们发现，经过几十年的时间，仍然没有达成共识，争论还延伸到振荡器是局部的，局限于基底膜上离散的局部源，还是全局的，在全局振荡器中，由内耳液耦合的一组微机械元件和基底膜部分在广泛的区域内相互作用。关于振荡器是最好用著名的范德波尔振荡器还是不太熟悉的杜芬或霍普夫振荡器来描述，也没有定论。我们发现不规则性在产生发射中起着关键作用。本文不是对 SOAEs 及其特性的系统回顾，而是对各种振荡器配置应用于人类耳朵建模的方式的历史调查。结论是，局部和全局方法之间的区别并不明显，它们可能不是相互排斥的概念。尽管如此，当人们看到人类 SOAEs 与某些振荡器排列如此紧密地匹配时，戈尔德无疑会说我们走在正确的轨道上。
