Department of Otolaryngology-Head and Neck Surgery, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112, USA.
J Acoust Soc Am. 2012 Sep;132(3):1636-45. doi: 10.1121/1.4742730.
High-speed videoendoscopy (HSV) enables the observation and measurement of vibratory behaviors of vocal folds by capturing the laryngeal imagery at high frame rates. The frame rates of commercially available HSVs, however, are still limited to carry out sample-based time-domain objective analyses. To mitigate the resulting lack of temporal resolution, existing studies have employed sum-of-harmonics parametric models to evaluate temporal vocal-fold behaviors. This paper focuses on the other weakness of HSV: its inherent susceptibility to temporal aliasing. Aliasing occurs when there are substantial harmonics above the Nyquist frequency of the HSV camera, and video cameras offer very little means to filter out these harmonics. Although the aliasing effect in HSV data minimally affects many of the laryngeal objective parameter measurements, some parameters, such as harmonics-to-noise ratio and derivative-based parameters, are sensitive to the aliased content. The use of a parametric model with a careful selection of the number of harmonics enables classification of the aliased harmonics as a part of the harmonic signal. Glottal area waveform examples are included to illustrate the modeling capability for cases of normal and disordered vocal folds.
高速视频内镜 (HSV) 通过以高帧率捕捉喉部图像，实现对声带振动行为的观察和测量。然而，商业上可用的 HSV 的帧率仍然限于进行基于样本的时域客观分析。为了减轻由此导致的时间分辨率不足的问题，现有研究采用了谐波和参数模型来评估时域声带行为。本文关注 HSV 的另一个弱点：其对时间混叠的固有敏感性。当 HSV 摄像机的奈奎斯特频率以上存在大量谐波时，就会发生混叠，而摄像机几乎没有办法滤除这些谐波。尽管 HSV 数据中的混叠效应对许多喉部客观参数测量的影响很小，但有些参数，如谐波与噪声比和基于导数的参数，对混叠内容很敏感。使用具有仔细选择谐波数量的参数模型，可以将混叠谐波分类为谐波信号的一部分。本文还包括声门区面积波形示例，以说明对正常和异常声带的建模能力。
