Brungart D S, Rabinowitz W M
Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge 02139, USA.
J Acoust Soc Am. 1999 Sep;106(3 Pt 1):1465-79. doi: 10.1121/1.427180.
Although researchers have long recognized the unique properties of the head-related transfer function (HRTF) for nearby sources (within 1 m of the listener's head), virtually all of the HRTF measurements described in the literature have focused on source locations 1 m or farther from the listener. In this study, HRTFs for sources at distances from 0.12 to 1 m were calculated using a rigid-sphere model of the head and measured using a Knowles Electronic Manikin for Acoustic Research (KEMAR) and an acoustic point source. Both the calculations and the measurements indicate that the interaural level difference (ILD) increases substantially for lateral sources as distance decreases below 1 m, even at low frequencies where the ILD is small for distant sources. In contrast, the interaural time delay (ITD) is roughly independent of distance even when the source is close. The KEMAR measurements indicate that the direction of the source relative to the outer ear plays an important role in determining the high-frequency response of the HRTF in the horizontal plane. However, the elevation-dependent characteristics of the HRTFs are not strongly dependent on distance, and the contribution of the pinna to the HRTF is independent of distance beyond a few centimeters from the ear. Overall, the results suggest that binaural cues play an important role in auditory distance perception for nearby sources.
尽管研究人员早就认识到头部相关传递函数（HRTF）对于附近声源（距离听者头部1米以内）的独特特性，但文献中描述的几乎所有HRTF测量都集中在距离听者1米或更远的声源位置。在本研究中，使用头部的刚性球体模型计算了距离在0.12至1米之间的声源的HRTF，并使用用于声学研究的诺尔斯电子人体模型（KEMAR）和声点源进行了测量。计算和测量结果均表明，对于侧向声源，当距离减小到1米以下时，双耳声级差（ILD）会大幅增加，即使在低频时，远距离声源的ILD很小。相比之下，即使声源很近，双耳时间延迟（ITD）也大致与距离无关。KEMAR测量表明，声源相对于外耳的方向在确定水平面上HRTF的高频响应方面起着重要作用。然而，HRTF的仰角相关特性并不强烈依赖于距离，耳廓对HRTF的贡献在距离耳朵几厘米以外时与距离无关。总体而言，结果表明双耳线索在附近声源的听觉距离感知中起着重要作用。
