Picker Engineering Program, Smith College, Northampton, 01063, MA, USA.
Boys Town National Research Hospital, Omaha, 68131, NE, USA.
Hear Res. 2023 Jul;434:108782. doi: 10.1016/j.heares.2023.108782. Epub 2023 Apr 29.
Description of the ear canal's geometry is essential for describing peripheral sound flow, yet physical measurements of the canal's geometry are lacking and recent measurements suggest that older-adult-canal areas are systematically larger than previously assumed. Methods to measure ear-canal geometry from multi-planar reconstructions of high-resolution CT images were developed and applied to 66 ears from 47 subjects, ages 18-90 years. The canal's termination, central axis, entrance, and first bend were identified based on objective definitions, and the canal's cross-sectional area was measured along its canal's central axis in 1-2 mm increments. In general, left and right ears from a given subject were far more similar than measurements across subjects, where areas varied by factors of 2-3 at many locations. The canal areas varied systematically with age cohort at the first-bend location, where canal-based measurement probes likely sit; young adults (18-30 years) had an average area of 44mm whereas older adults (61-90 years) had a significantly larger average area of 69mm. Across all subjects ages 18-90, measured means ± standard deviations included: canals termination area at the tympanic annulus 56±8mm; area at the canal's first bend 53±18mm; area at the canal's entrance 97±24mm; and canal length 31.4±3.1mm.
描述耳道的几何形状对于描述外围声音的流动至关重要，但目前缺乏对耳道几何形状的物理测量，并且最近的测量结果表明，老年人的耳道区域比之前假设的要大。我们开发了一种从高分辨率 CT 图像的多平面重建中测量耳道几何形状的方法，并将其应用于 47 名年龄在 18 至 90 岁的 66 只耳朵。根据客观定义确定了耳道的末端、中心轴、入口和第一弯曲处，并沿着中心轴以 1-2 毫米的增量测量耳道的横截面积。通常，同一受试者的左右耳比跨受试者的测量值更相似，在许多位置，面积相差 2-3 倍。在第一弯曲处，即可能放置基于耳道的测量探头的位置，耳道区域与年龄组系统相关；年轻成年人（18-30 岁）的平均面积为 44mm，而年长成年人（61-90 岁）的平均面积明显较大，为 69mm。在所有年龄在 18 至 90 岁的受试者中，测量的平均值±标准偏差包括：鼓膜环处的耳道末端面积为 56±8mm；第一弯曲处的面积为 53±18mm；入口处的面积为 97±24mm；以及耳道长度为 31.4±3.1mm。
