Membranous and cartilaginous vocal fold adduction in singing.

While vocal fold adduction is an important parameter in speech, relatively little has been known on the adjustment of the vocal fold adduction in singing. This study investigates the possibility of separate adjustments of cartilaginous and membranous vocal fold adduction in singing. Six female and seven male subjects, singers and non-singers, were asked to imitate an instructor in producing four phonation types: "aBducted falsetto" (FaB), "aDducted falsetto" (FaD), "aBducted Chest" (CaB), and "aDducted Chest" (CaD). The phonations were evaluated using videostroboscopy, videokymography (VKG), electroglottography (EGG), and audio recordings. All the subjects showed less posterior (cartilaginous) vocal fold adduction in phonation types FaB and CaB than in FaD and CaD, and less membranous vocal fold adduction (smaller closed quotient) in FaB and FaD than in CaB and CaD. The findings indicate that the exercises enabled the singers to separately manipulate (a) cartilaginous adduction and (b) membranous medialization of the glottis though vocal fold bulging. Membranous adduction (monitored via videokymographic closed quotient) was influenced by both membranous medialization and cartilaginous adduction. Individual control over these types of vocal fold adjustments allows singers to create different vocal timbres.

Depth-kymography of vocal fold vibrations: part II. Simulations and direct comparisons with 3D profile measurements.

We report novel direct quantitative comparisons between 3D profiling measurements and simulations of human vocal fold vibrations. Until now, in human vocal folds research, only imaging in a horizontal plane was possible. However, for the investigation of several diseases, depth information is needed, especially when the two folds act differently, e.g. in the case of tumour growth. Recently, with our novel depth-kymographic laryngoscope, we obtained calibrated data about the horizontal and vertical positions of the visible surface of the vibrating vocal folds. In order to find relations with physical parameters such as elasticity and damping constants, we numerically simulated the horizontal and vertical positions and movements of the human vocal folds while vibrating and investigated the effect of varying several parameters on the characteristics of the phonation: the masses and their dimensions, the respective forces and pressures, and the details of the vocal tract compartments. Direct one-to-one comparison with measured 3D positions presents-for the first time-a direct means of validation of these calculations. This may start a new field in vocal folds research.

Clinical evaluation of a membrane-based voice-producing element for laryngectomized women.

BACKGROUND: A newly developed artificial voice source was clinically evaluated in laryngectomized women for voice quality improvements. The prosthesis was placed in a commercially available, tracheoesophageal shunt valve. METHODS: In 17 subjects, voice-producing element (VPE) prototypes were compared with the subject's regular tracheo-esophageal shunt voice in a randomized cross-over trial. The evaluation was based on aeroacoustic measurements and perceptual analysis. RESULTS: Considerably higher fundamental frequencies were attained with the use of the VPE. The sound pressure level also increased for most subjects. The required driving pressures of the lung and air flow rates were altered, allowing significantly longer phonation times in 1 breath. Accumulation of mucus did not interfere with the proper functioning of the device during these tests. CONCLUSION: A VPE with sound-generating membranes is suitable for providing a substitute voice source for laryngectomized patients, especially patients suggestive of a severely hypotonic or atonic pharyngoesophageal segment who can benefit from a more melodious and louder voice.

Depth-kymography: high-speed calibrated 3D imaging of human vocal fold vibration dynamics.

We designed and developed a laser line-triangulation endoscope compatible with any standard high-speed camera for a complete three-dimensional profiling of human vocal fold vibration dynamics. With this novel device we are able to measure absolute values of vertical and horizontal vibration amplitudes, length and width of vocal folds as well as the opening and closing velocities from a single in vivo measurement. We have studied, for the first time, the generation and propagation of mucosal waves by locating the position of its maximum vertical position and the propagation velocity. Precise knowledge about the absolute dimensions of human vocal folds and their vibration parameters has significant importance in clinical diagnosis and treatment as well as in fundamental research in voice. The new device can be used to investigate different kinds of pathological conditions including periodic or aperiodic vibrations. Consequently, the new device has significant importance in investigating vocal fold paralysis and in phonosurgical applications.

New laryngoscope for quantitative high-speed imaging of human vocal folds vibration in the horizontal and vertical direction.

We report the design of a novel laser line-triangulation laryngoscope for the quantitative visualization of the three-dimensional movements of human vocal folds during phonation. This is the first successful in vivo recording of the three-dimensional movements of human vocal folds in absolute values. Triangulation images of the vocal folds are recorded at the rate of 4000 fps with a resolution of 256x256 pixels. A special image-processing algorithm is developed to precisely follow the subpixel movements of the laser line image. Vibration profiles in both horizontal and vertical directions are calibrated and measured in absolute SI units with a resolution of +/-50 microm. We also present a movie showing the vocal folds dynamics in vertical cross section.

Real-time kymographic imaging for visualizing human vocal-fold vibratory function.

A stand-alone kymographic system for visualizing human vocal-fold vibration in real time is presented. By using a dual charge-coupled-device construction, the system not only provides kymographic images but also simultaneously presents structural images for navigating the endoscope to a desired position. With a temporal resolution of 7200 lines/s, the kymographic imaging produces a sufficient speed to investigate most types of vocal-fold vibrations. Moreover, by buffering the kymographic images during the vertical blanking periods, the system can retrieve an uninterrupted kymographic image sequence even though the television standard is used. The results from preliminary clinical evaluation present evidence that the real-time kymographic imaging substantially reduces the time required for functional evaluation of the vocal-fold vibrations.

A new generation videokymography for routine clinical vocal fold examination.

OBJECTIVE: This study aims to introduce a new-generation videokymographic system, which provides simultaneous laryngoscopic and kymographic image, for routine clinical vocal fold examination. STUDY DESIGN: The authors explored a new imaging method for diagnosis and evaluation of voice disorders. METHODS: The new-generation videokymographic system includes two charge-coupled device image sensors, a color area image sensor, and a monochromic high-speed line-scan image sensor. The high-speed line-scan image sensor is used to capture the kymogram, and the color area image sensor is used to obtain the laryngoscopic image. The two images can be displayed simultaneously on a video monitor or stored in a standard video recorder. Three subjects with nonpathologic voice were investigated in detail with the new videokymographic system. RESULTS: The high-quality laryngoscopic image and kymogram can be used directly for clinical purposes with no further postprocessing. The scan position of the kymogram is always indicated in the laryngoscopic image, which provides feedback for the operator to easily locate the expected scanning position. All varieties of vocal fold vibration, including irregular vibrations, phonation onset and offset, can be observed with the presented method. The continuous kymogram of the vocal fold vibration can be retrieved from a kymographic image sequence for quantitative analysis. CONCLUSIONS: The new-generation videokymography provides a simple, quick means to investigate vocal fold vibration, especially for voice disorders. It can emerge as an important tool for routine clinical vocal fold examination.

[Modeling vocal-fold vibration via integrating two-mass model with finite-element method].

Modeling vocal-fold vibration is extremely significant in realizing the vibration properties of human vocal folds and investigating their physiological and pathological characteristics. A combined model presented is two mass-finite element (T-F) model, which integrates all merits of both the finite element method (FEM) model and the asymmetric two-mass model of vocal folds. The high-speed glottis graph (HGG) can also be synthesized by the model. The result shows that T-F model can simulate the vibration behavior of normal and pathological vocal folds in a more realistic way with competitively computational speed. Therefore, the T-F model is helpful to gaining a thorough understanding of the vibration properties of vocal folds.

[Fast outlier detection for milk near-infrared spectroscopy analysis].

Near-infrared spectroscopy is a fast and efficient analytical technique based on multivariate calibration model, which correlates near-infrared spectra with the property of samples (such as concentration). The reliability of analytical results depends mostly on the accuracy of measured spectra. But outliers do not make for reliable data. The authors combined RHM (Resampling by Half-Means) with SHV (Smallest Half-Volume) method to detect the outliers of the near-infrared spectra of milk samples, and the results were satisfactory. The performance of the new method is superior to the traditional outliers detecting algorithms such as Mahalanobis distances and hat matrix leverage. And this combined method is simple and fast to use, conceptually clear, and numerically stable, so it is recommended to be used for the detection of multiple outliers in multivariate data, especially the online measurement and discriminant analysis.

An automatic method to quantify the vibration properties of human vocal folds via videokymography.

The study offers an automatical quantitative method to obtain vibration properties of human vocal folds via videokymography. The presented method is based on image processing, which combines an active contour model with a genetic algorithm to improve detecting precision and processing speed, can accurately extract the vibration wave in videokymograms and quantify the vibration properties in terms of eight typical parameters automatically. To verify the precision of the proposed algorithm, an indirect simulation setup of vocal folds has been performed. The verification result shows that the relative error of the entire simulation system is less than 5%. Applying the method to analyzing hundreds of videokymograms from 12 subjects, the result indicates that the vibration characteristics of vocal folds can be recognized more exactly, and diseases of the vocal folds can be diagnosed quantitatively.