外周听觉系统对声音的表达

Representation of Sound Waves in the Peripheral Auditory System

听觉系统可以精细地分辨声音在强度或音调上的变化,而实现这种性能的前提是听觉外周对声波信号精准的表达。基于这一点,将耳蜗基底膜看作离散余弦变换器,可将进入耳蜗的声音信号变换为一组神经输出,神经纤维的空间分布代表频率,神经脉冲频率代表信号强度。仿真结果表明,该模型不仅可以很好地表达声波信号与神经输出之间的对应关系,还可以模拟由于听觉外周的非线性特性而产生的各种现象。

The auditory system can distinguish very small changes both in amplitude and frequency of sound. To achieve this excellent function, the periphery auditory system has to express the sound wave entering into the inner ears exactly. Based on this point of view, the cochlear basilar membrane can be treated as a discrete cosine transformer by which the entering sound wave can be transformed into outputs of a population of auditory nerves： each fiber represents a frequency and its spike rate represents the corresponding amplitude. Simulations show that the model not only can describe the relationship between the sound wave and the output of auditory nerves perfectly, but aJso can be used to sJmuJate the nonJinear properties of the periphery auditory system.