RESUMEN
BACKGROUND AND OBJECTIVE: Laryngeal lesions are usually investigated by microlaryngoscopy, biopsy, and histopathology. This study aimed to evaluate the combined use of Narrow Band Imaging (NBI) and High-Speed Imaging (HSI) in the differentiation of glottic lesions in awake patients. STUDY DESIGN: Prospective diagnostic study. MATERIALS AND METHODS: Thirty-six awake patients with 41 glottic lesions were investigated with both NBI and HSI, and the suspected diagnoses were compared to the histopathological results of tissue biopsies taken during subsequent microlaryngoscopies. Of the 41 lesions, 28 were primary lesions and 13 recurrent lesions after previous laryngeal pathologies. RESULTS: Sensitivity, specificity, positive predictive value, and negative predictive value in the differentiation between benign/premalignant and malignant lesions with both NBI and HSI accounted to 100.0%, 79.4%, 50.0%, and 100.0%. Sensitivities and specificities were 100.0% and 85.7% for HSI alone, and 100.0% and 79.4% for NBI alone. Regarding only primary lesions the results were generally better with sensitivities and specificities of 100% and 81% for NBI, 100% and 84.2% for HSI and 100% and 85.7% for the combination of both methods, respectively. CONCLUSION: NBI and HSI both seem to be promising adjunct tools in the differentiation of various laryngeal lesions in awake patients with high sensitivities. Specificities, however, were moderate but could be increased when using NBI and HSI in combination in a subgroup of patients with only primary lesions. Although both methods still have limitations they might ameliorate the evaluation of suspicious laryngeal lesions in the future and could possibly spare patients from repeated invasive tissue biopsies. Lasers Surg. Med. 49:609-618, 2017. © 2017 Wiley Periodicals, Inc.
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Enfermedades de la Laringe/diagnóstico por imagen , Imagen Multimodal/métodos , Imagen de Banda Estrecha/métodos , Biopsia , Humanos , Enfermedades de la Laringe/patología , Laringoscopía , Estudios Prospectivos , Estudios Retrospectivos , Sensibilidad y Especificidad , Método Simple CiegoRESUMEN
Previous research has suggested that the peaks in the first derivative (dEGG) of the electroglottographic (EGG) signal are good approximate indicators of the events of glottal opening and closing. These findings were based on high-speed video (HSV) recordings with frame rates 10 times lower than the sampling frequencies of the corresponding EGG data. The present study attempts to corroborate these previous findings, utilizing super-HSV recordings. The HSV and EGG recordings (sampled at 27 and 44 kHz, respectively) of an excised canine larynx phonation were synchronized by an external TTL signal to within 0.037 ms. Data were analyzed by means of glottovibrograms, digital kymograms, the glottal area waveform and the vocal fold contact length (VFCL), a new parameter representing the time-varying degree of 'zippering' closure along the anterior-posterior (A-P) glottal axis. The temporal offsets between glottal events (depicted in the HSV recordings) and dEGG peaks in the opening and closing phase of glottal vibration ranged from 0.02 to 0.61 ms, amounting to 0.24-10.88% of the respective glottal cycle durations. All dEGG double peaks coincided with vibratory A-P phase differences. In two out of the three analyzed video sequences, peaks in the first derivative of the VFCL coincided with dEGG peaks, again co-occurring with A-P phase differences. The findings suggest that dEGG peaks do not always coincide with the events of glottal closure and initial opening. Vocal fold contacting and de-contacting do not occur at infinitesimally small instants of time, but extend over a certain interval, particularly under the influence of A-P phase differences.
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Perros/fisiología , Glotis/fisiología , Fonación , Grabación en Video , Animales , Femenino , Espectrografía del Sonido , Vibración , Pliegues Vocales/fisiologíaRESUMEN
Elephants' low-frequency vocalizations are produced by flow-induced self-sustaining oscillations of laryngeal tissue. To date, little is known in detail about the vibratory phenomena in the elephant larynx. Here, we provide a first descriptive report of the complex oscillatory features found in the excised larynx of a 25 year old female African elephant (Loxodonta africana), the largest animal sound generator ever studied experimentally. Sound production was documented with high-speed video, acoustic measurements, air flow and sound pressure level recordings. The anatomy of the larynx was studied with computed tomography (CT) and dissections. Elephant CT vocal anatomy data were further compared with the anatomy of an adult human male. We observed numerous unusual phenomena, not typically reported in human vocal fold vibrations. Phase delays along both the inferior-superior and anterior-posterior (A-P) dimension were commonly observed, as well as transverse travelling wave patterns along the A-P dimension, previously not documented in the literature. Acoustic energy was mainly created during the instant of glottal opening. The vestibular folds, when adducted, participated in tissue vibration, effectively increasing the generated sound pressure level by 12 dB. The complexity of the observed phenomena is partly attributed to the distinct laryngeal anatomy of the elephant larynx, which is not simply a large-scale version of its human counterpart. Travelling waves may be facilitated by low fundamental frequencies and increased vocal fold tension. A travelling wave model is proposed, to account for three types of phenomena: A-P travelling waves, 'conventional' standing wave patterns, and irregular vocal fold vibration.
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Elefantes/anatomía & histología , Elefantes/fisiología , Laringe/anatomía & histología , Laringe/fisiología , Acústica , Movimientos del Aire , Comunicación Animal , Animales , Femenino , Humanos , Masculino , Modelos Biológicos , Presión , Sonido , Tomografía Computarizada por Rayos X , Vibración , Grabación de Cinta de VideoRESUMEN
Recently, endoscopic high-speed laryngoscopy has been established for commercial use as a state-of-the-art technique to examine vocal fold kinematics. Since modern cameras provide sampling rates of several thousand frames per second, a high volume of data has to be considered for visual and objective analysis. A method for visualizing endoscopic high speed videos in three-dimensional cycle-based graphs combining and extending the approaches of phonovibrograms and electroglottographic wavegrams is presented. To build a phonovibrographic wavegram, individual cycles of a phonovibrogram are segmented, normalized in cycle duration, and concatenated over time. For analyzing purposes, the emerging three-dimensional scalar field is visualized with different rendering techniques providing information of different aspects of vocal fold kinematics. The phonovibrographic wavegram incorporates information about the glottal closure type, size, and location of the amplitudes, symmetry, periodicity, and phase information. The potential of the approach to visualize the characteristics of vocal fold vibration in a compact and intuitive way is demonstrated within two healthy and three pathologic subjects. The phonovibrographic wavegram allows a comprehensive analysis of vocal fold kinematics and reveals information that remains hidden with other visualization techniques.
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Interpretación de Imagen Asistida por Computador , Enfermedades de la Laringe/fisiopatología , Laringoscopía , Fonación , Grabación en Video , Pliegues Vocales/fisiopatología , Adulto , Fenómenos Biomecánicos , Estudios de Casos y Controles , Disfonía/fisiopatología , Femenino , Humanos , Enfermedades de la Laringe/diagnóstico , Masculino , Persona de Mediana Edad , Pólipos/fisiopatología , Valor Predictivo de las Pruebas , Factores de Tiempo , Vibración , Parálisis de los Pliegues Vocales/fisiopatología , Pliegues Vocales/patologíaRESUMEN
BACKGROUND: In infants and young children, a wide heterogeneity of foot shape is typical. Therefore, children, who are additionally influenced by rapid growth and maturation, are a very special cohort for foot measurements and the footwear industry. The importance of foot measurements for footwear fit, design, as well as clinical applications has been sufficiently described. New measurement techniques (3D foot scanning) allow the assessment of the individual foot shape. However, the validity in comparison to conventional methods remains unclear. Therefore, the purpose of this study was to compare 3D foot scanning with two established measurement methods (2D digital scanning/manual foot measurements). METHODS: Two hundred seventy seven children (125 m / 152 f; mean ± SD: 8.0 ± 1.5yrs; 130.2 ± 10.7cm; 28.0 ± 7.3kg) were included into the study. After collection of basic data (sex, age (yrs), body height (cm), body weight (kg)) geometry of the right foot was measured in static condition (stance) with three different measurement systems (fixed order): manual foot measurement, 2D foot scanning (2D desk scanner) and 3D foot scanning (hand-held 3D scanner). Main outcomes were foot length, foot width (projected; anatomical; instep), heel width and anatomical foot ball breadth. Analysis of variances for dependent samples was applied to test for differences between foot measurement methods (Post-hoc analysis: Tukey-Kramer-Test; α=0.05). RESULTS: Significant differences were found for all outcome measures comparing the three methods (p<0.0001). The span of foot length differences ranged from 3 to 6mm with 2D scans showing the smallest and 3D scans the largest deviations. Foot width measurements in comparison of 3D and 2D scans showed consistently higher values for 3D measurements with the differences ranging from 1mm to 3mm. CONCLUSIONS: The findings suggests that when comparing foot data, it is important to consider the differences caused by new measurement methods. Differences of about 0.6cm are relevant when measuring foot length, as this is the difference of a complete shoe size (Parisian point). Hence, correction factors may be required to compare the results of different measurements appropriately. The presented results may have relevance in the field of ergonomics (shoe industry) as well as clinical practice.
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Pie , Talón , Humanos , Niño , Preescolar , Pie/diagnóstico por imagen , Pesos y Medidas Corporales , ZapatosRESUMEN
OBJECTIVES: The goal of this study was to objectively quantify the changes in vocal fold vibratory characteristics before and after surgery with high-speed videoendoscopy and the image analysis tool phonovibrography. METHODS: High-speed videoendoscopic data, audio recordings, and Voice Handicap Index scores were collected from 8 subjects with a diagnosis of unilateral vocal fold polyps, before operation and at 1 week and 1 to 3 months after operation. We then analyzed the objective phonovibrographic patterns and parameters describing the vocal fold vibratory behavior. RESULTS: On phonovibrography, the visual representations of the vocal fold vibratory characteristics, from both the individual and the group data, demonstrated very different patterns before surgery and both 1 week and 1 to 3 months after surgery. The individual phonovibrograms obtained from the left and right true vocal folds clearly demonstrated the lesion site and its effects on the vocal fold vibratory characteristics for each subject. The improvements in amplitude and symmetry (relative vibratory amplitude and vibration amplitude symmetry) of vocal fold vibration were quantified; the difference was greatest between data from before surgery and data from 1 week after surgery. CONCLUSIONS: The visual phonovibrographic patterns and quantitative data revealed marked changes in vocal fold vibratory patterns after operation and continued improvement at 1 to 3 months.
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Endoscopía/métodos , Pólipos/cirugía , Pliegues Vocales/fisiopatología , Adulto , Femenino , Humanos , Procesamiento de Imagen Asistido por Computador , Masculino , Persona de Mediana Edad , Periodo Posoperatorio , Vibración , Grabación en Video , Adulto JovenRESUMEN
With the use of an endoscopic, high-speed camera, vocal fold dynamics may be observed clinically during phonation. However, observation and subjective judgment alone may be insufficient for clinical diagnosis and documentation of improved vocal function, especially when the laryngeal disease lacks any clear morphological presentation. In this study, biomechanical parameters of the vocal folds are computed by adjusting the corresponding parameters of a three-dimensional model until the dynamics of both systems are similar. First, a mathematical optimization method is presented. Next, model parameters (such as pressure, tension and masses) are adjusted to reproduce vocal fold dynamics, and the deduced parameters are physiologically interpreted. Various combinations of global and local optimization techniques are attempted. Evaluation of the optimization procedure is performed using 50 synthetically generated data sets. The results show sufficient reliability, including 0.07 normalized error, 96% correlation, and 91% accuracy. The technique is also demonstrated on data from human hemilarynx experiments, in which a low normalized error (0.16) and high correlation (84%) values were achieved. In the future, this technique may be applied to clinical high-speed images, yielding objective measures with which to document improved vocal function of patients with voice disorders.
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Simulación por Computador , Modelos Biológicos , Fonación , Pliegues Vocales/fisiología , Voz , Algoritmos , Fenómenos Biomecánicos , Femenino , Humanos , Laringoscopía , Masculino , Presión , Reproducibilidad de los Resultados , Vibración , Grabación en Video , Pliegues Vocales/anatomía & histologíaRESUMEN
Within this study a retrospective analysis of clinical voice perturbation measures, Dysphonia Severity Index and subjective perceived hoarseness was performed to determine their value under clinical aspects. The study included the data of 580 healthy and 1,700 pathologic voices, which were investigated under the following aspects. The relevant parameters were identified and their interrelation determined. Group differences between healthy and pathologic voices were figured out and investigated if voice quality measures allowed an automatic diagnosis of voice disorders. The analysis revealed significant changes between the clinical groups, which indicate the diagnostic relevance of voice quality measures. However, an individual diagnosis of the underlying voice disorder failed due to a vast spread of the parameter values within the respective groups. Classification accuracies of 75-90% were achieved. The high misclassification rate of up to 25% implied that in voice disorder diagnosis, the individual interpretation of the parameter values has to be done carefully.
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Diagnóstico por Computador , Disfonía/diagnóstico , Ronquera/diagnóstico , Espectrografía del Sonido , Calidad de la Voz , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Disfonía/clasificación , Disfonía/etiología , Femenino , Ronquera/clasificación , Ronquera/etiología , Humanos , Masculino , Persona de Mediana Edad , Adulto JovenRESUMEN
In this work a detection algorithm for mucosal wave propagation is presented. By incorporating physiological knowledge of mucosal wave properties and taking the segmented lateral movement of both vocal fold edges as a basis, the spatio-temporal position of the traveling mucosal wave is identified and quantitatively captured. The course of mucosal wave propagation can be successfully detected and analyzed with regard to discriminating different types of mucosal wave activity (in terms of spread velocity and symmetry). The preliminary results obtained for six exemplary laryngeal high-speed recordings are promising and demonstrate the potential of the proposed detection and objective description approach.
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Mucosa Laríngea/fisiología , Modelos Biológicos , Acústica del Lenguaje , Pliegues Vocales/fisiología , Voz/fisiología , Algoritmos , HumanosRESUMEN
Human voice originates from the three-dimensional (3D) oscillations of the vocal folds. In previous studies, biomechanical properties of vocal fold tissues have been predicted by optimizing the parameters of simple two-mass-models to fit its dynamics to the high-speed imaging data from the clinic. However, only lateral and longitudinal displacements of the vocal folds were considered. To extend previous studies, a 3D mass-spring, cover-model is developed, which predicts the 3D vibrations of the entire medial surface of the vocal fold. The model consists of five mass planes arranged in vertical direction. Each plane contains five longitudinal, mass-spring, coupled oscillators. Feasibility of the model is assessed using a large body of dynamical data previously obtained from excised human larynx experiments, in vivo canine larynx experiments, physical models, and numerical models. Typical model output was found to be similar to existing findings. The resulting model enables visualization of the 3D dynamics of the human vocal folds during phonation for both symmetric and asymmetric vibrations.
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Modelos Biológicos , Pliegues Vocales/fisiología , Presión del Aire , Algoritmos , Animales , Fenómenos Biomecánicos , Simulación por Computador , Bases de Datos Factuales , Perros , Estudios de Factibilidad , Glotis/fisiología , Humanos , Técnicas In Vitro , Laringe/fisiología , Periodicidad , Fonación/fisiología , VibraciónRESUMEN
The objective investigation of the dynamic properties of vocal fold vibrations demands the recording and further quantitative analysis of laryngeal high-speed video (HSV). Quantification of the vocal fold vibration patterns requires as a first step the segmentation of the glottal area within each video frame from which the vibrating edges of the vocal folds are usually derived. Consequently, the outcome of any further vibration analysis depends on the quality of this initial segmentation process. In this work we propose for the first time a procedure to fully automatically segment not only the time-varying glottal area but also the vocal fold tissue directly from laryngeal high-speed video (HSV) using a deep Convolutional Neural Network (CNN) approach. Eighteen different Convolutional Neural Network (CNN) network configurations were trained and evaluated on totally 13,000 high-speed video (HSV) frames obtained from 56 healthy and 74 pathologic subjects. The segmentation quality of the best performing Convolutional Neural Network (CNN) model, which uses Long Short-Term Memory (LSTM) cells to take also the temporal context into account, was intensely investigated on 15 test video sequences comprising 100 consecutive images each. As performance measures the Dice Coefficient (DC) as well as the precisions of four anatomical landmark positions were used. Over all test data a mean Dice Coefficient (DC) of 0.85 was obtained for the glottis and 0.91 and 0.90 for the right and left vocal fold (VF) respectively. The grand average precision of the identified landmarks amounts 2.2 pixels and is in the same range as comparable manual expert segmentations which can be regarded as Gold Standard. The method proposed here requires no user interaction and overcomes the limitations of current semiautomatic or computational expensive approaches. Thus, it allows also for the analysis of long high-speed video (HSV)-sequences and holds the promise to facilitate the objective analysis of vocal fold vibrations in clinical routine. The here used dataset including the ground truth will be provided freely for all scientific groups to allow a quantitative benchmarking of segmentation approaches in future.
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Endoscopía , Glotis/diagnóstico por imagen , Interpretación de Imagen Asistida por Computador , Laringe/diagnóstico por imagen , Redes Neurales de la Computación , Grabación en Video , Pliegues Vocales/diagnóstico por imagen , Adulto , Algoritmos , Puntos Anatómicos de Referencia , Bases de Datos como Asunto , Femenino , Humanos , Factores de TiempoRESUMEN
OBJECTIVE: The aim of the study was to determine whether cortical auditory potentials evoked by monosyllabic words beginning with a single consonant can be attributed to a combination of two N1/P2 complexes, temporally separated by voice-onset time (VOT). DESIGN: Cortical auditory-evoked potentials were recorded in seven normal-hearing young adults in response to two types of stimuli (a) simple tone bursts and (b) five monosyllabic words with different VOTs. Cortical burst responses (mainly consisting of N1 and P2) formed the basic functions for the simulation of speech-evoked potentials. Actually, two basic functions were created with respect to different VOTs of the speech sounds. An optimization procedure was used to determine the relative contributions of the two N1/P2 complexes. RESULTS: Speech-evoked potentials differed clearly across the stimuli. In all subjects, close matches of the synthetic and the measured waveforms could be gained for all speech sounds. The relative magnitudes of the constituent complexes differed among stimuli. CONCLUSIONS: The auditory-evoked response to a monosyllabic speech sound with short VOT can be represented by two overlapping N1/P2 complexes-one to syllable onset and the second to vowel onset. The temporal separation between the two components is well predicted by VOT, but the relative amplitudes vary across syllables. Observed variability in the fitting accuracy across subjects is small.
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Estimulación Acústica/métodos , Corteza Auditiva/fisiología , Potenciales Evocados Auditivos , Fonética , Voz , Adulto , Electroencefalografía , Femenino , Humanos , Masculino , Variaciones Dependientes del Observador , Tiempo de Reacción , Factores de Tiempo , Adulto JovenRESUMEN
Endoscopic high-speed laryngoscopy in combination with image analysis strategies is the most promising approach to investigate the interrelation between vocal fold vibrations and voice disorders. So far, due to the lack of an objective and standardized analysis procedure a unique characterization of vocal fold vibrations has not been achieved yet. We present a visualization and analysis strategy which transforms the segmented edges of vibrating vocal folds into a single 2-D image, denoted Phonovibrogram (PVG). Within a PVG the individual type of vocal fold vibration becomes uniquely characterized by specific geometric patterns. The PVG geometries give an intuitive access on the type and degree of the laryngeal asymmetry and can be quantified using an image segmentation approach. The PVG analysis was applied to 14 representative recordings derived from a high-speed database comprising normal and pathological voices. We demonstrate that PVGs are capable to differentiate and quantify different types of normal and pathological vocal fold vibrations. The objective and precise quantification of the PVG geometry may have the potential to realize a novel classification of vocal fold vibrations.
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Algoritmos , Interpretación de Imagen Asistida por Computador/métodos , Laringoscopía/métodos , Medición de la Producción del Habla/métodos , Grabación en Video/métodos , Pliegues Vocales/anatomía & histología , Pliegues Vocales/fisiología , Humanos , Aumento de la Imagen/métodos , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Procesamiento de Señales Asistido por Computador , VibraciónRESUMEN
OBJECTIVES: High-speed (HS) video recordings are the up-to-date method for visualizing irregular vocal fold vibrations. However, perceptive evaluation during offline replay is time consuming and shows high inter-rater variability. METHOD: A visualization procedure is presented that extracts vocal fold vibrations from HS videos and transfers the motion information into a set of three phonovibrogram (PVG) images that make visual vocal fold displacements (PVG-0), velocities (PVG-1), and accelerations (PVG-2). RESULTS: The principles of PVG computation as well as their application to three clinical examples (normal voice, laryngeal nerve paralysis, functional voice disorder with vocal nodules) are presented. For normal and dysphonic subjects, the PVG images show the characteristics of vocal fold vibrations as concern the dynamic patterns of displacements, velocities, and accelerations. CONCLUSION: The PVG approach makes visual the entire range of motion of vibrating vocal fold edges in easy-to-read color images for differentiation of normal and pathologic voices. PVG images are printable and can be stored on a hard-disc drive, enabling the documentation of the course of voice disorders that is essential for evidenced-based medicine. PVG visualization has the potential to overcome the subjective quality of assessing HS videos, which makes it a valuable tool with broad clinical application.
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Procesamiento de Imagen Asistido por Computador/métodos , Laringoscopía/métodos , Grabación en Video/métodos , Pliegues Vocales/fisiopatología , Aceleración , Adulto , Fenómenos Biomecánicos , Color , Femenino , Humanos , Almacenamiento y Recuperación de la Información , Enfermedades de la Laringe/fisiopatología , Masculino , Persona de Mediana Edad , Espectrografía del Sonido/métodos , Factores de Tiempo , Vibración , Parálisis de los Pliegues Vocales/fisiopatología , Pliegues Vocales/patología , Voz/fisiología , Trastornos de la Voz/fisiopatologíaRESUMEN
A model-based approach is proposed to objectively measure and classify vocal fold vibrations by left-right asymmetries along the anterior-posterior direction, especially in the case of nonstationary phonation. For this purpose, vocal fold dynamics are recorded in real time with a digital high-speed camera during phonation of sustained vowels as well as pitch raises. The dynamics of a multimass model with time-dependent parameters are matched to vocal fold vibrations extracted at dorsal, medial, and ventral positions by an automatic optimization procedure. The block-based optimization accounts for nonstationary vibrations and compares the vocal fold and model dynamics by wavelet coefficients. The optimization is verified with synthetically generated data sets and is applied to 40 clinical high-speed recordings comprising normal and pathological voice subjects. The resulting model parameters allow an intuitive visual assessment of vocal fold instabilities within an asymmetry diagram and are applicable to an objective quantification of asymmetries.
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Modelos Biológicos , Percepción Espacial , Percepción del Habla , Percepción del Tiempo , Pliegues Vocales/fisiología , Humanos , Medición de la Producción del Habla , VibraciónRESUMEN
Pathologic changes within the organic constitution of vocal folds or a functional impairment of the larynx may result in disturbed or even irregular vocal fold vibrations. The consequences are perturbations of the acoustic speech signal which are perceived as a hoarse voice. By means of appropriate image processing techniques, the vocal fold dynamics are extracted from digital high-speed videos. This study addresses the approach to obtain a parametric description of the spatio-temporal characteristics of the vocal fold oscillations for the aim of classification. For this purpose a biomechanical vocal fold model is introduced. An automatic optimization procedure is developed for fitting the model dynamics to the observed vocal fold oscillations. Thus, the resulting parameter values represent a specific vibration pattern and serve as an objective quantification measure. Performance and reliability of the optimization procedure are validated with synthetically generated data sets. The high-speed videos of two normal voice subjects and six patients suffering from different voice disorders are processed. The resulting model parameters represent a rough approximation of physiological parameters along the entire vocal folds.
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Grabación en Video , Pliegues Vocales/fisiología , Voz , Algoritmos , Fenómenos Biomecánicos , Endoscopía , Glotis/anatomía & histología , Glotis/fisiología , Humanos , Modelos Biológicos , Oscilometría , Fotograbar , Vibración , Pliegues Vocales/anatomía & histologíaRESUMEN
Investigation of voice disorders requires the examination of vocal fold vibrations. State of the art is the recording of endoscopic high-speed movies which capture vocal fold vibrations in real-time. It enables investigating the interrelation between disturbances of vocal fold vibrations and voice disorders. However, the lack of clinical studies and of a standardized procedure to reconstruct vocal fold vibrations from high-speed videos constrain the clinical acceptance of the high-speed technique. An image processing approach is presented that extracts the vibrating vocal fold edges from digital high-speed movies. The initial segmentation is principally based on a seeded region-growing algorithm. Even in movies with low image quality the algorithm segments successfully the glottal area by an introduced two-dimensional threshold matrix. Following segmentation, the vocal fold edges are reconstructed from the computed time-varying glottal area. The performance of the procedure was objectively evaluated within a study comprising 372 high-speed recordings. The accuracy of vocal fold reconstruction exceeds manual segmentation results obtained by clinical experts. The algorithm reaches an information flow-rate of up to 98 images per second. The robustness and high accuracy of the procedure makes it suitable for the application in clinical routine. It enables an objective and highly accurate description of vocal fold vibrations which is essential to realize extensive clinical studies which focus on the classification of voice disorders.
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Endoscopía/métodos , Grabación de Cinta de Video/métodos , Pliegues Vocales/fisiología , Algoritmos , Humanos , VibraciónRESUMEN
Event-related potentials (ERPs) as part of the EEG are applied to assess auditory processing in children. Mismatch negativity (MMN) is a change-specific component of ERPs that indicates a pre-cognitive discrimination process. MMN responses were recorded in 10 healthy preschool children to four different types of signal changes. The signals investigated were processed using a discrete wavelet transform (DWT) to analyze the characteristics of the ERP components. All children showed distinct MMN that was significant in all tasks. The MMN amplitudes varied between subjects and depended on the different tasks. The wavelet transform allowed simplified analysis and quantification of the MMN component, as well as the double-peak structure of the P1 component. The variation in MMN amplitudes suggests the possibility of determining individual auditory profiles. Owing to the shorter time required, the MMN paradigm suggested combined with the DWT proposed offers a new objective investigation method for children.
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Algoritmos , Inteligencia Artificial , Diagnóstico por Computador/métodos , Electroencefalografía/métodos , Potenciales Evocados Auditivos/fisiología , Reconocimiento de Normas Patrones Automatizadas/métodos , Procesamiento de Señales Asistido por Computador , Niño , Preescolar , Análisis Discriminante , Femenino , Humanos , Masculino , Reproducibilidad de los Resultados , Tamaño de la Muestra , Sensibilidad y EspecificidadRESUMEN
Hoarseness in unilateral vocal fold paralysis is mainly due to irregular vocal fold vibrations caused by asymmetries within the larynx physiology. By means of a digital high-speed camera vocal fold oscillations can be observed in real-time. It is possible to extract the irregular vocal fold oscillations from the high-speed recordings using appropriate image processing techniques. An inversion procedure is developed which adjusts the parameters of a biomechanical model of the vocal folds to reproduce the irregular vocal fold oscillations. Within the inversion procedure a first parameter approximation is achieved through a knowledge-based algorithm. The final parameter optimization is performed using a genetic algorithm. The performance of the inversion procedure is evaluated using 430 synthetically generated data sets. The evaluation results comprise an error estimation of the inversion procedure and show the reliability of the algorithm. The inversion procedure is applied to 15 healthy voice subjects and 15 subjects suffering from unilateral vocal fold paralysis. The optimized parameter sets allow a classification of pathologic and healthy vocal fold oscillations. The classification may serve as a basis for therapy selection and quantification of therapy outcome in case of unilateral vocal fold paralysis.
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Endoscopía/métodos , Interpretación de Imagen Asistida por Computador/métodos , Modelos Biológicos , Procesamiento de Señales Asistido por Computador , Medición de la Producción del Habla/métodos , Grabación en Video/métodos , Parálisis de los Pliegues Vocales/diagnóstico , Algoritmos , Inteligencia Artificial , Relojes Biológicos , Fenómenos Biomecánicos/métodos , Humanos , Movimiento , Reconocimiento de Normas Patrones Automatizadas/métodos , Parálisis de los Pliegues Vocales/clasificación , Parálisis de los Pliegues Vocales/fisiopatologíaRESUMEN
OBJECTIVE: This work presents a computer-based approach to analyze the two-dimensional vocal fold dynamics of endoscopic high-speed videos, and constitutes an extension and generalization of a previously proposed wavelet-based procedure. While most approaches aim for analyzing sustained phonation conditions, the proposed method allows for a clinically adequate analysis of both dynamic as well as sustained phonation paradigms. MATERIALS AND METHODS: The analysis procedure is based on a spatio-temporal visualization technique, the phonovibrogram, that facilitates the documentation of the visible laryngeal dynamics. From the phonovibrogram, a low-dimensional set of features is computed using a principle component analysis strategy that quantifies the type of vibration patterns, irregularity, lateral symmetry and synchronicity, as a function of time. Two different test bench data sets are used to validate the approach: (I) 150 healthy and pathologic subjects examined during sustained phonation. (II) 20 healthy and pathologic subjects that were examined twice: during sustained phonation and a glissando from a low to a higher fundamental frequency. In order to assess the discriminative power of the extracted features, a Support Vector Machine is trained to distinguish between physiologic and pathologic vibrations. The results for sustained phonation sequences are compared to the previous approach. Finally, the classification performance of the stationary analyzing procedure is compared to the transient analysis of the glissando maneuver. RESULTS: For the first test bench the proposed procedure outperformed the previous approach (proposed feature set: accuracy: 91.3%, sensitivity: 80%, specificity: 97%, previous approach: accuracy: 89.3%, sensitivity: 76%, specificity: 96%). Comparing the classification performance of the second test bench further corroborates that analyzing transient paradigms provides clear additional diagnostic value (glissando maneuver: accuracy: 90%, sensitivity: 100%, specificity: 80%, sustained phonation: accuracy: 75%, sensitivity: 80%, specificity: 70%). CONCLUSIONS: The incorporation of parameters describing the temporal evolvement of vocal fold vibration clearly improves the automatic identification of pathologic vibration patterns. Furthermore, incorporating a dynamic phonation paradigm provides additional valuable information about the underlying laryngeal dynamics that cannot be derived from sustained conditions. The proposed generalized approach provides a better overall classification performance than the previous approach, and hence constitutes a new advantageous tool for an improved clinical diagnosis of voice disorders.