Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, MA 02114, USA.
Hear Res. 2012 Aug;290(1-2):83-90. doi: 10.1016/j.heares.2012.04.011. Epub 2012 May 16.
This study investigates the ossicular motion produced by bone-conducted (BC) sound in live human ears. Laser Doppler vibrometry was used to measure air conduction (AC)- and BC-induced umbo velocity (V(U)) in both ears of 10 subjects, 20 ears total. Sound pressure in the ear canal (P(EC)) was measured simultaneously. For air conduction, V(U) at standard hearing threshold level was calculated. For BC, ΔV was defined as the difference between V(U) and the tympanic ring velocity (an estimate of the skull velocity measured in the ear canal). ΔV and P(EC) at BC standard hearing threshold were calculated. ΔV at standard BC threshold was significantly smaller than V(U) at standard AC threshold between 500 Hz and 2000 Hz. Ear canal pressure at BC threshold tended to be smaller than for AC below 3000 Hz (with significant differences at 1000 Hz and 2000 Hz). Our results are most consistent with inertia of the ossicles and cochlear fluid driving BC hearing below 500 Hz, but with other mechanisms playing a significant role at higher frequencies. Sound radiated into the external ear canal might contribute to BC hearing at 3000 Hz and above.
本研究旨在探讨骨导（BC）声音在活体人耳中产生的听骨运动。本研究采用激光多普勒测振仪测量了 10 名受试者 20 只耳朵的空气传导（AC）和骨导引起的鼓岬速度（V(U)）。同时测量了耳道中的声压（P(EC)）。对于空气传导，计算了标准听阈水平下的 V(U)。对于骨导，ΔV 定义为 V(U)与鼓膜环速度（在耳道中测量的颅骨速度的估计值）之间的差异。计算了骨导标准听阈下的ΔV 和 P(EC)。在 500Hz 至 2000Hz 范围内，骨导标准阈值下的 ΔV 明显小于 AC 标准阈值下的 V(U)。在 3000Hz 以下，骨导阈值下的耳道压力趋于小于 AC（在 1000Hz 和 2000Hz 时存在显著差异）。我们的结果最符合在 500Hz 以下，由听骨惯性和耳蜗液体驱动骨导听力的理论，但在更高频率时，其他机制也发挥了重要作用。辐射到外耳道的声音可能有助于 3000Hz 及以上的骨导听力。
