Middlebrooks J C
Kresge Hearing Research Institute, University of Michigan, Ann Arbor 48109-0506, USA.
J Acoust Soc Am. 1999 Sep;106(3 Pt 1):1480-92. doi: 10.1121/1.427176.
This study examined inter-subject differences in the transfer functions from the free field to the human ear canal, which are commonly know as head-related transfer functions. The directional components of such transfer functions are referred here to as directional transfer functions (DTFs). The DTFs of 45 subjects varied systematically among subjects in regard to the frequencies of spectral features such as peaks and notches. Inter-subject spectral differences in DTFs were quantified between 3.7 and 12.9 kHz for sound-source directions throughout the coordinate sphere. For each pair of subjects, an optimal frequency scale factor aligned spectral features between subjects and, thus, minimized inter-subject spectral differences. Frequency scaling of DTFs reduced spectral differences by a median value of 15.5% across all pairs of subjects and by more than half in 9.5% of subject pairs. Optimal scale factors showed a median value of 1.061 and a maximum of 1.38. The optimal scale factor between any pair of subjects correlated highly with the ratios of subjects' maximum interaural delays, sizes of their external ears, and widths of their heads.
本研究考察了从自由场到人类耳道的传递函数中的个体差异，这些传递函数通常被称为头部相关传递函数。此类传递函数的方向分量在此被称为方向传递函数（DTF）。45名受试者的DTF在诸如峰值和凹口等频谱特征的频率方面在个体间存在系统性差异。在整个坐标球的声源方向上，对3.7至12.9千赫之间的DTF个体间频谱差异进行了量化。对于每一对受试者，一个最优频率比例因子使个体间的频谱特征对齐，从而使个体间频谱差异最小化。DTF的频率缩放使所有受试者对之间的频谱差异中位数降低了15.5%，在9.5%的受试者对中降低了一半以上。最优比例因子的中位数为1.061，最大值为1.38。任意一对受试者之间的最优比例因子与受试者最大耳间延迟的比率、其外耳大小以及头部宽度高度相关。
