DIRECTIONAL SENSITIVITY OF SOUND-PRESSURE LEVELS IN THE HUMAN EAR CANAL
DIRECTIONAL SENSITIVITY OF SOUND-PRESSURE LEVELS IN THE HUMAN EAR CANAL
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DOI：
10.1121/1.398224
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发表时间：
1989-07-01
影响因子：
2.4
通讯作者：
GREEN, DM
中科院分区：
文献类型：
--
作者：
MIDDLEBROOKS, JC;MAKOUS, JC;GREEN, DM
报告了位于受试者周围不同位置的宽带声源在耳道中测量的声压变化。这些位置相关的压力是人类听众进行声音定位的声学线索的一个来源。以10 °的水平和垂直分辨率测试声源位置。声级是用放置在两个耳道内的微型麦克风测量的。虽然测得的幅度谱随麦克风在耳道中的位置而变化，但结果表明，在任何特定频率的宽带刺激的方向灵敏度与麦克风在耳道内的任何位置无关。在任何给定的频率下，作为声源位置的函数的声压分布形成特征空间模式，该特征空间模式包括一个或两个离散区域，声源从该离散区域在耳道中产生最大水平。这些离散区域的位置根据声音频率在水平和垂直位置上变化。例如，在8kHz附近，通常发现两个最大灵敏度区域位于横向并且彼此垂直分离，而在12kHz附近，发现两个这样的区域位于水平面上并且水平分离。不同受试者的声音水平的空间模式非常相似，尽管需要一些频率缩放来适应受试者身体大小的差异。在低于约8 kHz的频率下，声压级（ILD）的耳间差异往往随着声源距额中线的距离的增加而单调增加，并且往往相对恒定，作为垂直源位置的函数。然而，在较高的频率下，ILD随着声源的水平和垂直位置而变化。在某些频率下，给定受试者的左右耳之间的不对称性甚至对于中线声源也会导致大量ILD。这些结果表明的类型的水平和垂直的空间信息，可从声级线索在不同的频率范围内，并在一个小的主题人群，指示受试者间的变异性的性质。
Changes in sound pressures measured in the ear canal are reported for broadband sound sources positioned at various locations about the subject. These location-dependent pressures are one source of acoustical cues for sound localization by human listeners. Sound source locations were tested with horizontal and vertical resolution of 10.degree.. Sound levels were measured with miniature microphones placed inside the two ear canals. Although the measured amplitude spectra varied with the position of the microphone in the ear canal, it is shown that the directional sensitivity at any particular frequency of the broadband stimulus is independent of microphone position anywhere within the ear canal. At any given frequency, the distribution of sound pressures as a function of sound source location formed a characteristic spatial pattern comprising one or two discrete areas from which sound sources produced maximum levels in the ear canal. The locations of these discrete areas varied in horizontal and vertical location according to sound frequency. For example, around 8 kHz, two areas of maximum sensitivity typically were found that were located laterally and were separated from each other vertically, whereas, around 12 kHz, two such areas were found located on the horizontal plane and separated horizontally. The spatial patterns of sound levels were remarkably similar mong different subjects, although some frequency scaling was required to accommodate for differences in the subjects'' physical sizes. Interaural differences in sound-pressure level (ILDs) at frequencies below about 8 kHz tended to increase monotonically with increasing distance of the sound source from the frontal midline and tended to be relatively constant as a function of vertical source location. At higher frequencies, however ILDs varied both with the horizontal and with the vertical location of the sound source. At some frequencies, asymmetries between the left and right ears in a given subject resulted in substantial ILDs even for midline sound sources. These results indicate the types of horizontal and vertical spatial information that are available from sound level cues over various ranges of frequency and, within a small subject population, indicate the nature of intersubject variability.