Celik Hüseyin, Cankurtaran Mehmet, Cakmak Ozcan
Department of Physics, Faculty of Engineering, Hacettepe University, Beytepe, 06532 Ankara, Turkey.
Phys Med Biol. 2004 Feb 7;49(3):371-86. doi: 10.1088/0031-9155/49/3/002.
Stepped-tube models with a constriction in the anterior section were used to evaluate the effects that nasal valve passage area and nasal cavity shape have on acoustic rhinometry (AR) measurements. The AR-determined cross-sectional areas beyond a constriction of small passage area were consistently underestimated, and the corresponding area-distance curves showed pronounced oscillations. Also, the AR technique did not accurately reproduce abrupt changes in passage area. The results suggest that, regardless of the particular shape of the nasal cavity model, AR does not provide reliable information about cross-sectional areas posterior to a severe constriction. The experimental results are discussed in terms of theoretically calculated acoustic input impedance for the models studied, the physical limitations of AR, and assumptions made in AR algorithms. The study demonstrated that energy losses and sound wave attenuation due to air viscosity do not significantly affect AR measurements. It was also shown that passage area beyond a severe constriction is underestimated because the barrier created by the constriction reflects most of the incident sound power. The results also indicate that the oscillations in area-distance curves are due to low-frequency acoustic resonances in the nasal cavity model.
使用在前部有缩窄的阶梯管模型来评估鼻瓣通道面积和鼻腔形状对鼻声反射（AR）测量的影响。由AR测定的小通道面积缩窄后的横截面积一直被低估，并且相应的面积-距离曲线显示出明显的振荡。此外，AR技术不能准确再现通道面积的突然变化。结果表明，无论鼻腔模型的具体形状如何，AR都不能提供关于严重缩窄后部横截面积的可靠信息。根据所研究模型的理论计算声学输入阻抗、AR的物理局限性以及AR算法中所做的假设，对实验结果进行了讨论。该研究表明，由于空气粘性导致的能量损失和声波衰减不会显著影响AR测量。研究还表明，严重缩窄后的通道面积被低估是因为缩窄形成的屏障反射了大部分入射声功率。结果还表明，面积-距离曲线中的振荡是由于鼻腔模型中的低频声学共振。
