Tollin Daniel J, Koka Kanthaiah
Department of Physiology and Biophysics, University of Colorado Health Sciences Center, Aurora, Colorado 80045, USA.
J Acoust Soc Am. 2009 Feb;125(2):980-94. doi: 10.1121/1.3058630.
Although there have been many anatomical, physiological, and psychophysical studies of auditory development in cat, there have been no comparable studies of the development of the sound pressured transformations by the cat head and pinnae. Because the physical dimensions of the head and pinnae determine the spectral and temporal transformations of sound, as head and pinnae size increase during development, the magnitude and frequency ranges of these transformations are hypothesized to systematically change. This hypothesis was tested by measuring directional transfer functions (DTFs), the directional components of head-related transfer functions, and the linear dimensions of the head and pinnae in cats from the onset of hearing ( approximately 1.5 weeks) through adulthood. Head and pinnae dimensions increased by factors of approximately 2 and approximately 2.5, respectively, reaching adult values by approximately 23 and approximately 16 weeks, respectively. The development of the spectral notch cues to source location, the spatial- and frequency-dependent distributions of DTF amplitude gain (acoustic directionality), maximum gain, and the acoustic axis, and the resonance frequency and associated gain of the ear canal and concha were systematically related to the dimensions of the head and pinnae. These monaural acoustical properties of the head and pinnae in the cat are mature by 16 weeks.
尽管已经有许多关于猫听觉发育的解剖学、生理学和心理物理学研究，但对于猫头和耳廓对声压变换的发育情况，却没有类似的研究。由于头和耳廓的物理尺寸决定了声音的频谱和时间变换，随着发育过程中头和耳廓尺寸的增加，这些变换的幅度和频率范围被假设会系统性地变化。通过测量从听力开始（约1.5周）到成年期猫的方向传递函数（DTF）、头相关传递函数的方向分量以及头和耳廓的线性尺寸，对这一假设进行了检验。头和耳廓尺寸分别增加了约2倍和约2.5倍，分别在约23周和约16周时达到成年值。声源位置的频谱凹陷线索、DTF幅度增益（声学方向性）的空间和频率依赖性分布、最大增益以及声轴，以及耳道和耳甲的共振频率和相关增益的发育，都与头和耳廓的尺寸系统相关。猫的头和耳廓的这些单耳声学特性在16周时成熟。
