Concurrent Development of the Head and Pinnae and the Acoustical Cues to Sound Location in a Precocious Species, the Chinchilla (Chinchilla lanigera)
Concurrent Development of the Head and Pinnae and the Acoustical Cues to Sound Location in a Precocious Species, the Chinchilla (Chinchilla lanigera)
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DOI：
10.1007/s10162-010-0242-3
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发表时间：
2011-04-01
影响因子：
2.4
通讯作者：
Tollin, Daniel J.
中科院分区：
文献类型：
--
作者：
Jones, Heath G.;Koka, Kanthaiah;Tollin, Daniel J.
声音通过头部和耳廓以空间和频率依赖的方式过滤，从而产生声源位置的声学线索。这些光谱和时间变换取决于头部和耳廓的物理尺寸。因此，双耳声音定位线索的幅度-两耳间时间（ITD）和电平（ILD）的差异-被假设为系统地增加，而大量ILD生产的频率下限预计将减少，由于在发展过程中的头部和耳廓大小的增加。单声道频谱陷波提示源海拔的频率范围也预计会减少。这一假设在这里进行了测试，通过测量方向传递函数（DTFs），头部相关的传递函数的方向组件，以及龙猫从出生到成年的头部和pinthelas的线性尺寸。头部和耳廓的尺寸分别增加了1.8和2.42倍，达到成人值相似的6周。从DTF，ITD，ILD和频谱形状线索计算。最大ITDs增加了1.75倍，从出生时的160亩（P0-1，出生后第一天）到成人的280亩。ILD取决于源位置和频率，随着头部和针头尺寸的增加，ILD的频率范围（> 10 dB）从较高频率向较低频率偏移。频谱陷波频率也观察到类似的趋势，范围从P0-1的14.7-33.4 kHz到成人的5.3-19.1 kHz。频谱陷波线索的发展，DTF幅度增益，声学方向性，最大增益，和声轴的空间和频率相关的分布系统地与头部和pinnacle的尺寸。龙猫头部和耳廓的尺寸以及与之相关的声学特性在6周左右就成熟了。
Sounds are filtered in a spatial- and frequency-dependent manner by the head and pinna giving rise to the acoustical cues to sound source location. These spectral and temporal transformations are dependent on the physical dimensions of the head and pinna. Therefore, the magnitudes of binaural sound location cues-the interaural time (ITD) and level (ILD) differences-are hypothesized to systematically increase while the lower frequency limit of substantial ILD production is expected to decrease due to the increase in head and pinna size during development. The frequency ranges of the monaural spectral notch cues to source elevation are also expected to decrease. This hypothesis was tested here by measuring directional transfer functions (DTFs), the directional components of head-related transfer functions, and the linear dimensions of the head and pinnae for chinchillas from birth through adulthood. Dimensions of the head and pinna increased by factors of 1.8 and 2.42, respectively, reaching adult values by similar to 6 weeks. From the DTFs, the ITDs, ILDs, and spectral shape cues were computed. Maximum ITDs increased by a factor of 1.75, from similar to 160 mu s at birth (P0-1, first postnatal day) to 280 mu s in adults. ILDs depended on source location and frequency exhibiting a shift in the frequency range of substantial ILD (> 10 dB) from higher to lower frequencies with increasing head and pinnae size. Similar trends were observed for the spectral notch frequencies which ranged from 14.7-33.4 kHz at P0-1 to 5.3-19.1 kHz in adults. The development of the spectral notch cues, the spatial- and frequency-dependent distributions of DTF amplitude gain, acoustic directionality, maximum gain, and the acoustic axis were systematically related to the dimensions of the head and pinnae. The dimension of the head and pinnae in the chinchilla as well as the acoustical properties associated with them are mature by similar to 6 weeks.