Estimation of Subglottal Pressure, Vocal Fold Collision Pressure, and Intrinsic Laryngeal Muscle Activation From Neck-Surface Vibration Using a Neural Network Framework and a Voice Production Model

The ambulatory assessment of vocal function can be significantly enhanced by having access to physiologically based features that describe underlying pathophysiological mechanisms in individuals with voice disorders. This type of enhancement can improve methods for the prevention, diagnosis, and treatment of behaviorally based voice disorders. Unfortunately, the direct measurement of important vocal features such as subglottal pressure, vocal fold collision pressure, and laryngeal muscle activation is impractical in laboratory and ambulatory settings. In this study, we introduce a method to estimate these features during phonation from a neck-surface vibration signal through a framework that integrates a physiologically relevant model of voice production and machine learning tools. The signal from a neck-surface accelerometer is first processed using subglottal impedance-based inverse filtering to yield an estimate of the unsteady glottal airflow. Seven aerodynamic and acoustic features are extracted from the neck surface accelerometer and an optional microphone signal. A neural network architecture is selected to provide a mapping between the seven input features and subglottal pressure, vocal fold collision pressure, and cricothyroid and thyroarytenoid muscle activation. This non-linear mapping is trained solely with 13,000 Monte Carlo simulations of a voice production model that utilizes a symmetric triangular body-cover model of the vocal folds. The performance of the method was compared against laboratory data from synchronous recordings of oral airflow, intraoral pressure, microphone, and neck-surface vibration in 79 vocally healthy female participants uttering consecutive /pæ/ syllable strings at comfortable, loud, and soft levels. The mean absolute error and root-mean-square error for estimating the mean subglottal pressure were 191 Pa (1.95 cm H2O) and 243 Pa (2.48 cm H2O), respectively, which are comparable with previous studies but with the key advantage of not requiring subject-specific training and yielding more output measures. The validation of vocal fold collision pressure and laryngeal muscle activation was performed with synthetic values as reference. These initial results provide valuable insight for further vocal fold model refinement and constitute a proof of concept that the proposed machine learning method is a feasible option for providing physiologically relevant measures for laboratory and ambulatory assessment of vocal function.Fil: Ibarra, Emiro J.. Universidad Tecnica Federico Santa Maria.; ChileFil: Parra, Jesús A.. Universidad Tecnica Federico Santa Maria.; ChileFil: Alzamendi, Gabriel Alejandro. Universidad Nacional de Entre Ríos. Instituto de Investigación y Desarrollo en Bioingeniería y Bioinformática - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigación y Desarrollo en Bioingeniería y Bioinformática; ArgentinaFil: Cortés, Juan P.. Universidad Tecnica Federico Santa Maria.; ChileFil: Espinoza, Víctor M.. Universidad de Chile; ChileFil: Mehta, Daryush D.. Center For Laryngeal Surgery And Voice Rehabilitation; Estados UnidosFil: Hillman, Robert E.. Center For Laryngeal Surgery And Voice Rehabilitation; Estados UnidosFil: Zañartu, Matías. Universidad Tecnica Federico Santa Maria.; Chil

Direct measurement and modeling of intraglottal, subglottal, and vocal fold collision pressures during phonation in an individual with a hemilaryngectomy

The purpose of this paper is to report on the first in vivo application of a recently developed transoral, dual-sensor pressure probe that directly measures intraglottal, subglottal, and vocal fold collision pressures during phonation. Synchronous measurement of intraglottal and subglottal pressures was accomplished using two miniature pressure sensors mounted on the end of the probe and inserted transorally in a 78-year-old male who had previously undergone surgical removal of his right vocal fold for treatment of laryngeal cancer. The endoscopist used one hand to position the custom probe against the surgically medialized scar band that replaced the right vocal fold and used the other hand to position a transoral endoscope to record laryngeal high-speed videoendoscopy of the vibrating left vocal fold contacting the pressure probe. Visualization of the larynx during sustained phonation allowed the endoscopist to place the dual-sensor pressure probe such that the proximal sensor was positioned intraglottally and the distal sensor subglottally. The proximal pressure sensor was verified to be in the strike zone of vocal fold collision during phonation when the intraglottal pressure signal exhibited three characteristics: an impulsive peak at the start of the closed phase, a rounded peak during the open phase, and a minimum value around zero immediately preceding the impulsive peak of the subsequent phonatory cycle. Numerical voice production modeling was applied to validate model-based predictions of vocal fold collision pressure using kinematic vocal fold measures. The results successfully demonstrated feasibility of in vivo measurement of vocal fold collision pressure in an individual with a hemilaryngectomy, motivating ongoing data collection that is designed to aid in the development of vocal dose measures that incorporate vocal fold impact collision and stresses.Fil: Mehta, Daryush D.. Massachusetts General Hospital; Estados UnidosFil: Kobler, James B.. Massachusetts General Hospital; Estados UnidosFil: Zeitels, Steven M.. Harvard Medical School. Department of Medicine. Massachusetts General Hospital; Estados UnidosFil: Zañartu, Matías. Universidad Técnica Federico Santa María; ChileFil: Ibarra, Emiro J.. Universidad Técnica Federico Santa María; ChileFil: Alzamendi, Gabriel Alejandro. Universidad Nacional de Entre Ríos. Instituto de Investigación y Desarrollo en Bioingeniería y Bioinformática - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigación y Desarrollo en Bioingeniería y Bioinformática; ArgentinaFil: Manriquez, Rodrigo. Universidad Técnica Federico Santa María; ChileFil: Erath, Byron D.. Clarkson University; Estados UnidosFil: Peterson, Sean D.. University of Waterloo; CanadáFil: Petrillo, Robert H.. Center For Laryngeal Surgery and Voice Rehabilitation; Estados UnidosFil: Hillman, Robert E.. Center For Laryngeal Surgery and Voice Rehabilitation; Estados Unidos. Harvard Medical School. Department of Medicine. Massachusetts General Hospital; Estados Unido

Using Ambulatory Voice Monitoring to Investigate Common Voice Disorders: Research Update

Many common voice disorders are chronic or recurring conditions that are likely to result from inefficient and/or abusive patterns of vocal behavior, referred to as vocal hyperfunction. The clinical management of hyperfunctional voice disorders would be greatly enhanced by the ability to monitor and quantify detrimental vocal behaviors during an individual’s activities of daily life. This paper provides an update on ongoing work that uses a miniature accelerometer on the neck surface below the larynx to collect a large set of ambulatory data on patients with hyperfunctional voice disorders (before and after treatment) and matched-control subjects. Three types of analysis approaches are being employed in an effort to identify the best set of measures for differentiating among hyperfunctional and normal patterns of vocal behavior: (1) ambulatory measures of voice use that include vocal dose and voice quality correlates, (2) aerodynamic measures based on glottal airflow estimates extracted from the accelerometer signal using subject-specific vocal system models, and (3) classification based on machine learning and pattern recognition approaches that have been used successfully in analyzing long-term recordings of other physiological signals. Preliminary results demonstrate the potential for ambulatory voice monitoring to improve the diagnosis and treatment of common hyperfunctional voice disorders

Electrooxidation of 2,4,6-trichlorophenol on glassy carbon electrodes modified with composite Ni(oh)2-co(oh)2 films

Glassy carbon electrodes coated with a film of electrodeposited cobalt and nickel hydroxides were prepared in order to determine its activity to the 2,4,6-trichlorophenol (TCP) oxidation. The modified electrodes were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy and Scan Electron Microscopy (SEM) with Energy Dispersive X-ray Spectroscopy (EDS). The results indicate that both hydroxides are homogeneously distributed in the electrode surface. From the viewpoint of electrochemical oxidation of TCP, the presence of cobalt and nickel hydroxides on the electrode surface (i) promotes a more complete oxidation of TCP and (ii) decreases the fouling of the electrode surface in comparison with GC and GC modified with Ni or Co separately.Peer Reviewe

Preparation and characterization of bimetallic Fe-Cu allophane nanoclays and their activity in the phenol oxidation by heterogeneous electro-Fenton reaction

Bimetallic (Fe-Cu) allophane nanoclays were synthesized using a two-step wet impregnation method with different Fe/Cu ratios. The catalytic activities of bimetallic (Fe-Cu) allophane were studied for phenol oxidation by heterogeneous electro-Fenton reaction (HEF) at different initial pHs (3.0 and 5.5), and were compared with Fe-allophane and Cu-allophane catalysts. A glassy carbon electrode modified with the bimetallic allophane nanoclays was used as working electrode. FTIR, SEM, X-ray diffraction, XPS, Mössbauer spectroscopy and N adsorption-desorption were used to characterize the catalysts, and indicated the formation of small copper oxide particles stabilized by iron oxide species. Phenol conversion by HEF process at initial pH 3.0 was near 100% for all bimetallic (Fe-Cu) allophane nanoclays in less than 2 h of reaction, following an exponential decay. The chemical oxygen demand (COD) removal was less than 47% for Cu-allophane and 65% for Fe-allophane, whereas for the bimetallic (Fe-Cu) allophane nanoclays the COD removal decreased with the amount of copper oxide in the catalyst, achieving an 80% COD removal with FeCu catalyst. These results showed the synergetic effect between the Fe and Cu ions present in the bimetallic (Fe-Cu) allophane nanoclays. Similarly, when the reactions were performed at initial pH 5.5 the phenol conversion was near 100% after 4 h for Fe-allophane and bimetallic (Fe-Cu) allophane with lower copper content. In the bimetallic (Fe-Cu) allophane clays the leaching of iron and copper into the solution was less than 1.25 mg/L and 0.638 mg/L, respectively, indicative of the high stability of the bimetallic (Fe-Cu) allophane catalysts.Peer Reviewe

On the dramatic increase with chain length of the oxidazability of linear saturated aliphatic alcohols on gold in alkaline media

© 2015 Elsevier Ltd. All rights reserved. The electrooxidation of linear saturated aliphatic alcohols from C1 to C8 on gold in alkaline media has been studied by cyclic voltammetry and with an electrochemical quartz crystal microbalance. The current density of alcohol oxidation very markedly increased and, correspondingly, the onset potential decreased, with increasing chain length, that is, with initially slightly increasing, and then constant, pKa. We attribute this oxidazability increase with chain length to the increasing hydrophobicity of the alcohol. Effectively, a molecular dynamics simulation of the hydration of alcohols and alcoholates shows that the hydrophobicity of the alcohols increases with increasing chain length. The higher activity of gold for the oxidation of organic, and also inorganic (CO), compounds in alkaline media is well known, and should be due to an activation of the gold surface by OH adsorption, and not to a change of the compounds themselves, the (majority) neutral alcohol being the oxidized species both in acid and alkaline media. At the potentials at which 1-heptanol oxidation starts, the mass in both base electrolyte and in 1-heptanol is at a minimum, or nearly so, which shows that water is driven away from the surface of gold prior to the oxidation of both gold and 1-heptanol.Peer Reviewe

The difference between first and second harmonic amplitudes correlates between glottal airflow and neck-surface accelerometer signals during phonation

Miniature high-bandwidth accelerometers on the anterior neck surface are used in laboratory and ambulatory settings to obtain vocal function measures. This study compared the widely applied L1-L2 measure (historically, H1-H2) - the difference between the log-magnitude of the first and second harmonics - computed from the glottal airflow waveform with L1-L2 derived from the raw neck-surface acceleration signal in 79 vocally healthy female speakers. Results showed a significant correlation (r = 0.72) between L1-L2 values estimated from both airflow and accelerometer signals, suggesting that raw accelerometer-based estimates of L1-L2 may be interpreted as reflecting glottal physiological parameters and voice quality attributes during phonation