Fadaei Mohaddeseh, Abouali Omid, Emdad Homayoun, Faramarzi Mohammad, Ahmadi Goodarz
a School of Mechanical Engineering, Shiraz University , Shiraz , Iran.
Comput Methods Biomech Biomed Engin. 2015;18(16):1797-810. doi: 10.1080/10255842.2014.974578. Epub 2014 Dec 16.
In this study, a numerical investigation is performed to evaluate the effects of high-pressure sinusoidal and blast wave's propagation around and inside of a human external ear. A series of computed tomography images are used to reconstruct a realistic three-dimensional (3D) model of a human ear canal and the auricle. The airflow field is then computed by solving the governing differential equations in the time domain using a computational fluid dynamics software. An unsteady algorithm is used to obtain the high-pressure wave propagation throughout the ear canal which is validated against the available analytical and numerical data in literature. The effects of frequency, wave shape, and the auricle on pressure distribution are then evaluated and discussed. The results clearly indicate that the frequency plays a key role on pressure distribution within the ear canal. At 4 kHz frequency, the pressure magnitude is much more amplified within the ear canal than the frequencies of 2 and 6 kHz, for the incident wave angle of 90° investigated in this study, attributable to the '4-kHz notch' in patients with noise-induced hearing loss. According to the results, the pressure distribution patterns at the ear canal are very similar for both sinusoidal pressure waveform with the frequency of 2 kHz and blast wave. The ratio of the peak pressure value at the eardrum to that at the canal entrance increases from about 8% to 30% as the peak pressure value of the blast wave increases from 5 to 100 kPa for the incident wave angle of 90° investigated in this study. Furthermore, incorporation of the auricle to the ear canal model is associated with centerline pressure magnitudes of about 50% and 7% more than those of the ear canal model without the auricle throughout the ear canal for sinusoidal and blast waves, respectively, without any significant effect on pressure distribution pattern along the ear canal for the incident wave angle of 90° investigated in this study.
在本研究中，进行了数值研究以评估高压正弦波和冲击波在人外耳周围及内部传播的影响。使用一系列计算机断层扫描图像重建了人耳道和耳廓的逼真三维（3D）模型。然后通过使用计算流体动力学软件在时域中求解控制微分方程来计算气流场。采用非定常算法来获得高压波在整个耳道中的传播情况，并与文献中可用的分析和数值数据进行验证。随后评估并讨论了频率、波形和耳廓对压力分布的影响。结果清楚地表明，频率在耳道内的压力分布中起着关键作用。对于本研究中研究的90°入射波角度，在4 kHz频率下，耳道内的压力幅值比2 kHz和6 kHz频率下放大得多，这归因于噪声性听力损失患者的“4 kHz陷波”。根据结果，对于频率为2 kHz的正弦压力波形和冲击波，耳道处的压力分布模式非常相似。对于本研究中研究的90°入射波角度，随着冲击波的峰值压力值从5 kPa增加到100 kPa，鼓膜处的峰值压力值与耳道入口处的峰值压力值之比从约8%增加到30%。此外，对于正弦波和冲击波，将耳廓纳入耳道模型后，在整个耳道内，中心线压力幅值分别比没有耳廓的耳道模型高约50%和7%，而对于本研究中研究的90°入射波角度，对沿耳道的压力分布模式没有任何显著影响。
