ANALYSIS OF VOCAL FOLD KINEMATICS USING HIGH SPEED VIDEO

Vocal folds are the twin in-folding of the mucous membrane stretched horizontally across the larynx. They vibrate modulating the constant air flow initiated from the lungs. The pulsating pressure wave blowing through the glottis is thus the source for voiced speech production. Study of vocal fold dynamics during voicing are critical for the treatment of voice pathologies. Since the vocal folds move at 100 - 350 cycles per second, their visual inspection is currently done by strobosocopy which merges information from multiple cycles to present an apparent motion. High Speed Digital Laryngeal Imaging(HSDLI) with a temporal resolution of up to 10,000 frames per second has been established as better suited for assessing the vocal fold vibratory function through direct recording. But the widespread use of HSDLI is limited due to lack of consensus on the modalities like features to be examined. Development of the image processing techniques which circumvents the need for the tedious and time consuming effort of examining large volumes of recording has room for improvement. Fundamental questions like the required frame rate or resolution for the recordings is still not adequately answered. HSDLI cannot get the absolute physical measurement of the anatomical features and vocal fold displacement. This work addresses these challenges through improved signal processing. A vocal fold edge extraction technique with subpixel accuracy, suited even for hard to record pediatric population is developed first. The algorithm which is equally applicable for pediatric and adult subjects, is implemented to facilitate user inspection and intervention. Objective features describing the fold dynamics, which are extracted from the edge displacement waveform are proposed and analyzed on a diverse dataset of healthy males, females and children. The sampling and quantization noise present in the recordings are analyzed and methods to mitigate them are investigated. A customized Kalman smoothing and spline interpolation on the displacement waveform is found to improve the feature estimation stability. The relationship between frame rate, spatial resolution and vibration for efficient capturing of information is derived. Finally, to address the inability to measure physical measurement, a structured light projection calibrated with respect to the endoscope is prototyped

AUDIO SCENE SEGEMENTATION USING A MICROPHONE ARRAY AND AUDITORY FEATURES

Auditory stream denotes the abstract effect a source creates in the mind of the listener. An auditory scene consists of many streams, which the listener uses to analyze and understand the environment. Computer analyses that attempt to mimic human analysis of a scene must first perform Audio Scene Segmentation (ASS). ASS find applications in surveillance, automatic speech recognition and human computer interfaces. Microphone arrays can be employed for extracting streams corresponding to spatially separated sources. However, when a source moves to a new location during a period of silence, such a system loses track of the source. This results in multiple spatially localized streams for the same source. This thesis proposes to identify local streams associated with the same source using auditory features extracted from the beamformed signal. ASS using the spatial cues is first performed. Then auditory features are extracted and segments are linked together based on similarity of the feature vector. An experiment was carried out with two simultaneous speakers. A classifier is used to classify the localized streams as belonging to one speaker or the other. The best performance was achieved when pitch appended with Gammatone Frequency Cepstral Coefficeints (GFCC) was used as the feature vector. An accuracy of 96.2% was achieved

Effects of Vocal Fold Nodules on Glottal Cycle Measurements Derived from High-Speed Videoendoscopy in Children

The goal of this study is to quantify the effects of vocal fold nodules on vibratory motion in children using high-speed videoendoscopy. Differences in vibratory motion were evaluated in 20 children with vocal fold nodules (5–11 years) and 20 age and gender matched typically developing children (5–11 years) during sustained phonation at typical pitch and loudness. Normalized kinematic features of vocal fold displacements from the mid-membranous vocal fold point were extracted from the steady-state high-speed video. A total of 12 kinematic features representing spatial and temporal characteristics of vibratory motion were calculated. Average values and standard deviations (cycle-to-cycle variability) of the following kinematic features were computed: normalized peak displacement, normalized average opening velocity, normalized average closing velocity, normalized peak closing velocity, speed quotient, and open quotient. Group differences between children with and without vocal fold nodules were statistically investigated. While a moderate effect size was observed for the spatial feature of speed quotient, and the temporal feature of normalized average closing velocity in children with nodules compared to vocally normal children, none of the features were statistically significant between the groups after Bonferroni correction. The kinematic analysis of the mid-membranous vocal fold displacement revealed that children with nodules primarily differ from typically developing children in closing phase kinematics of the glottal cycle, whereas the opening phase kinematics are similar. Higher speed quotients and similar opening phase velocities suggest greater relative forces are acting on vocal fold in the closing phase. These findings suggest that future large-scale studies should focus on spatial and temporal features related to the closing phase of the glottal cycle for differentiating the kinematics of children with and without vocal fold nodules

Effects of Vocal Fold Nodules on Glottal Cycle Measurements Derived from High-Speed Videoendoscopy in Children

<div><p>The goal of this study is to quantify the effects of vocal fold nodules on vibratory motion in children using high-speed videoendoscopy. Differences in vibratory motion were evaluated in 20 children with vocal fold nodules (5–11 years) and 20 age and gender matched typically developing children (5–11 years) during sustained phonation at typical pitch and loudness. Normalized kinematic features of vocal fold displacements from the mid-membranous vocal fold point were extracted from the steady-state high-speed video. A total of 12 kinematic features representing spatial and temporal characteristics of vibratory motion were calculated. Average values and standard deviations (cycle-to-cycle variability) of the following kinematic features were computed: normalized peak displacement, normalized average opening velocity, normalized average closing velocity, normalized peak closing velocity, speed quotient, and open quotient. Group differences between children with and without vocal fold nodules were statistically investigated. While a moderate effect size was observed for the spatial feature of speed quotient, and the temporal feature of normalized average closing velocity in children with nodules compared to vocally normal children, none of the features were statistically significant between the groups after Bonferroni correction. The kinematic analysis of the mid-membranous vocal fold displacement revealed that children with nodules primarily differ from typically developing children in closing phase kinematics of the glottal cycle, whereas the opening phase kinematics are similar. Higher speed quotients and similar opening phase velocities suggest greater relative forces are acting on vocal fold in the closing phase. These findings suggest that future large-scale studies should focus on spatial and temporal features related to the closing phase of the glottal cycle for differentiating the kinematics of children with and without vocal fold nodules.</p></div

Right and left vocal fold displacement waveforms normalized by glottal length (<i>G</i>_<i>L</i>) and cycle period for a (a) child with nodules and (b) without nodules.

<p>Darker line denotes the displacement of the left vocal fold. The thin line is the displacement of the right vocal fold.</p

Illustration of critical points on displacement waveforms.

<p>Time-axis shows normalized glottal cycles and annotations show notation for denoted key events in the cycle, <i>n</i>_<i>m</i> = start opening phase, <i>n</i>_<i>pm</i> = peak displacement, <i>n</i>_<i>cm</i> = start of closed phase.</p

Comparison across standard deviation of the kinematic features between children with and without nodules.

<p>Comparison across standard deviation of the kinematic features between children with and without nodules.</p

Shapiro-Wilk test of normality for the mean values of the kinematic features.

<p>Shapiro-Wilk test of normality for the mean values of the kinematic features.</p

Laser-Induced Breakdown Spectroscopy (LIBS) for the Detection of Rare Earth Elements (REEs) in Meteorites

The spectroscopic characterization of plasma generated in meteorite samples during Laser-Induced Breakdown Spectroscopy (LIBS) shows the emission spectrum of elements present and also allows one to rapidly identify the elemental composition without any sample preparation and with good accuracy compared to some other methods. In addition, LIBS has other advantages, such as multi-elemental response, micro–nano gram level of destructiveness and portability of the instrument. Since the presence of Rare Earth Elements (REEs) in meteorites is usually in trace levels or not at all, LIBS can be used as a potential alternative method for the meteorite fragment analysis which, in turn, gives valuable clues on its origin as well as the origin of the solar system and its impact on life on Earth, particularly on the presence of REEs. The elemental analysis results for a few of the selected samples, such as iron meteorites, lunar meteorites, eucrites and impact glass, are presented and discussed. The LIBS analysis was supplemented by Principal Component Analysis (PCA) with which it was possible to classify the samples into different classes according to their chief constituents, structure and origin

Laser-Induced Breakdown Spectroscopy (LIBS) for the Detection of Rare Earth Elements (REEs) in Meteorites

The spectroscopic characterization of plasma generated in meteorite samples during Laser-Induced Breakdown Spectroscopy (LIBS) shows the emission spectrum of elements present and also allows one to rapidly identify the elemental composition without any sample preparation and with good accuracy compared to some other methods. In addition, LIBS has other advantages, such as multi-elemental response, micro&ndash;nano gram level of destructiveness and portability of the instrument. Since the presence of Rare Earth Elements (REEs) in meteorites is usually in trace levels or not at all, LIBS can be used as a potential alternative method for the meteorite fragment analysis which, in turn, gives valuable clues on its origin as well as the origin of the solar system and its impact on life on Earth, particularly on the presence of REEs. The elemental analysis results for a few of the selected samples, such as iron meteorites, lunar meteorites, eucrites and impact glass, are presented and discussed. The LIBS analysis was supplemented by Principal Component Analysis (PCA) with which it was possible to classify the samples into different classes according to their chief constituents, structure and origin