DYNAMIC PROCESSES IN THE AUDITORY SYSTEM

听觉系统的一个基本属性是跟随的能力 振幅和频率随时间的变化。虽然我们 对听觉系统的静态特性有很多了解， 虽然被广泛研究，但其动态性能却不是很好 明白了。 有证据表明听觉的敏感度和调谐 系统可能作为先前刺激的函数而改变。实验 关于听觉过滤的时间发展已经表明 转弯似乎更锐利的信号出现延迟后 掩蔽物开始，相对于掩蔽物开始时出现的信号。 敏感度和调谐都可能改变的证据来自 这一现象称为超调。在一定的频率条件下 和级别，音调的阈值在音调开始时较高 MASKER比它延迟100毫秒或更多。其中最 通常提出的超调机制是，它反映了 短期神经适应。最近的一些证据表明，这 “适应”不是简单的信号频率疲劳，而可能是 由听觉中的神经反馈(或传出)环调节 系统。这将解释这样一个事实，即频率远离 信号频率至少对超调负有部分责任 效果。 这一证据和其他研究表明，潜在的影响 超调可以提供关于活动之间的关系的窗口 耳蜗滤过器和传出系统。尽管过滤器中的更改 形状本身不能解释超调的大小 效果，使用超调型范式将允许检查 独立适应和听觉滤过器的形状。听觉滤光器 形状没有在相同条件下直接测量 以超调的方式出现。该项目建议测量超调 和听觉过滤器形状相似的条件，并确定是否 听滤器的形状似乎随着刺激而变窄 出现过冲的情况，而不是 看不到超调。这对于理解 正常听力中的活动过程及其对听力的影响 减损。

A fundamental property of the auditory system is the ability to follow changes in amplitude and frequency over time. Although we understand a good deal about static properties of the auditory system, the dynamic properties, although extensively researched, are less well understood. There is evidence that the sensitivity and tuning of the auditory system may change as a function of prior stimulation. Experiments on the temporal development of auditory filtering have shown that turning appears to be sharper for a signal presented with a delay after masker onset, relative to a signal presented at masker onset. Evidence that both sensitivity and tuning may change comes from a phenomenon called overshoot. Under certain conditions of frequency and level, the threshold for the tone is higher on the onset of the masker than it is after a delay of 100 ms or more. One of the most commonly proposed mechanisms for overshoot is that it reflects short-term neural adaptation. Some recent evidence suggests that this 'adaptation' is not simple fatigue at the signal frequency, but may be mediated by a neural feedback (or efferent) loop in the auditory system. This would explain the fact that frequencies remote from the signal frequency are at least partially responsible for the overshoot effect. This evidence and other research suggest that the effects underlying overshoot may provide a window on the relationship between active cochlear filtering and the efferent system. Although change in filter shape by itself cannot account for the magnitude of the overshoot effect, using an overshoot-type paradigm would allow examination of adaptation ad auditory filtershape independently. Auditory filter shapes have not been directly measured under the same conditions present in overshoot. This project proposes to measure overshoot and auditory filter shapes I similar conditions, and determine whether auditory filter shapes appear to narrow with stimulation under conditions in which overshoot is seen, and not in conditions in which overshoot is not seen. This has implications for understanding of the active process in normal hearing and for the effects of hearing impairment.