Powers N L, Salvi R J, Wang J, Spongr V, Qiu C X
Department of Communicative Disorders & Sciences, Buffalo 14214, USA.
Nature. 1995 Jun 15;375(6532):585-7. doi: 10.1038/375585a0.
The inner ear sometimes acts as a robust sound generator, continuously broadcasting sounds (spontaneous otoacoustic emissions) which can be intense enough to be heard by other individuals standing nearby. Paradoxically, most individuals are unaware of the sounds generated within their ears. Two hypotheses could explain this paradox: (1) the spontaneous emissions may not be transmitted to the central nervous system; or (2) the spontaneous emission produces a continuous, high rate of neural activity, which, like the natural pattern of spontaneous activity, is ignored by the central nervous system. Here we demonstrate that high-intensity spontaneous otoacoustic emission can vigorously activate auditory nerve fibres in mammals (Chinchilla laniger). This 'internal biological noise' creates a 'line busy' signal that significantly degrades a neuron's ability to respond to sound and results in a hearing loss completely different from that caused by damage to sensory cells.
内耳有时会充当一个强大的声音发生器，持续发出声音（自发性耳声发射），其强度足以让站在附近的其他人听到。矛盾的是，大多数人并未意识到自己耳内产生的声音。有两种假说可以解释这一矛盾现象：（1）自发性发射可能不会传递到中枢神经系统；或者（2）自发性发射会产生持续的、高频率的神经活动，就像自然的自发性活动模式一样，会被中枢神经系统忽略。在此，我们证明高强度的自发性耳声发射能够有力地激活哺乳动物（毛丝鼠）的听神经纤维。这种“内部生物噪声”会产生一个“线路繁忙”信号，显著降低神经元对声音的反应能力，并导致一种与感觉细胞受损所引起的听力损失完全不同的听力损失。
