Vertical Phase Differences Research Articles

Laryngeal and Acoustic Analysis of Chest and Head Registers Extended Across a Three-Octave Range: A Case Study

Voice registers are assumed to be related to different laryngeal adjustments, but objective evidence has been insufficient. While chest register is usually associated with the lower pitch range, and head register with the higher pitch range, here we investigated a professional singer who claimed an ability to produce both these registers at every pitch, throughout her entire singing range. The singer performed separated phonations alternating between the two registers (further called chest-like and head-like) at all pitches from C3 (131 Hz) to C6 (1047 Hz). We monitored the vocal fold vibrations using high-speed video endoscopy and electroglottography. The microphone sound was recorded and used for blind listening tests performed by the three authors (insiders) and by six "naive" participants (outsiders). The outsiders correctly identified the registers in 64% of the cases, and the insiders in 89% of the cases. Objective analysis revealed larger closed quotient and vertical phase differences for the chest-like register within the lower range below G4 (<392 Hz), and also a larger closed quotient at the membranous glottis within the higher range above Bb4 (>466 Hz), but not between Ab4-A4 (415-440 Hz). The normalized amplitude quotient was consistently lower in the chest-like register throughout the entire range. The results indicate that that the singer employed subtle laryngeal control mechanisms for the chest-like and head-like phonations on top of the traditionally recognized low-pitched chest and high-pitched head register phenomena. Across all pitches, the chest-like register was produced with more rapid glottal closure that was usually, but not necessarily, accompanied also by stronger adduction of membranous glottis. These register changes were not always easily perceivable by listeners, however.

Using vertical phase differences to better resolve 3D gravity wave structure

Abstract. Atmospheric gravity waves (GWs) are a critically important dynamical mechanism in the terrestrial atmosphere, with significant effects on weather and climate. They are geographically ubiquitous in the middle and upper atmosphere, and thus, satellite observations are key to characterising their properties and spatial distribution. Nadir-viewing satellite instruments characterise the short horizontal wavelength portion of the GW spectrum, which is important for momentum transport; however, these nadir-sensing instruments have coarse vertical resolutions. This restricts our ability to characterise the 3D structure of these waves accurately, with important implications for our quantitative understanding of how these waves travel and how they drive the atmospheric circulation when they break. Here, we describe, implement and test a new spectral analysis method to address this problem. This method is optimised for the characterisation of waves in any three-dimensional data set where one dimension is of coarse resolution relative to variations in the wave field, a description which applies to GW-sensing nadir-sounding satellite instruments but which is also applicable in other areas of science. We show that our new “2D + 1 ST” method provides significant benefits relative to existing spectrally isotropic methods for characterising such waves. In particular, it is much more able to detect regional and height variations in observed vertical wavelength and able to properly characterise extremely vertically long waves that extend beyond the data volume.

Modelling sagittal and vertical phase differences in a lumped and distributed elements vocal fold model

The quality and timbre of disordered voices heavily rely on the vibration properties of the vocal folds. We discuss the representation of sagittal phase differences in vocal fold oscillations through a numerical biomechanical model involving lumped elements as well as distributed elements, i.e., delay lines. A dynamic glottal source model is proposed in which the fold displacement along the vertical and the sagittal dimensions is modelled using delay lines. In contrast to other models, with which the reproduction of sagittal phase differences is impossible (e.g., in two-mass models) or not easy to control (e.g., in 3D 16-mass and multi-mass models in general), the one proposed here provides direct control over the amount of phase delay between folds’ oscillations at the posterior and anterior part of the glottis, i.e., the sagittal axis, and at the superior and inferior part of the glottis, i.e., the vertical axis, while keeping the dynamic model simple and computationally efficient. The model is assessed by addressing the reproduction of oscillatory patterns observed in high-speed videoendoscopic data, in which sagittal phase differences are observed. Also, timing asymmetry parameters observed in hemi glottal area waveforms (GAWs) are used for fitting.

Visual and Automatic Evaluation of Vocal Fold Mucosal Waves Through Sharpness of Lateral Peaks in High-Speed Videokymographic Images

IntroductionThe sharpness of lateral peaks is a visually helpful clinical feature in high-speed videokymographic (VKG) images indicating vertical phase differences and mucosal waves on the vibrating vocal folds and giving insights into the health and pliability of vocal fold mucosa. This study aims at investigating parameters that can be helpful in objectively quantifying the lateral peak sharpness from the VKG images. MethodForty-five clinical VKG images with different degrees of sharpness of lateral peaks were independently evaluated visually by three raters. The ratings were compared to parameters obtained by automatic image analysis of the vocal fold contours: Open Time Percentage Quotients (OTQ) and Plateau Quotients (PQ). The OTQ parameters were derived as fractions of the period during which the vocal fold displacement exceeds a predetermined percentage of the vibratory amplitude. The PQ parameters were derived similarly but as a fraction of the open phase instead of a period. ResultsThe best correspondence between the visual ratings and the automatically derived quotients were found for the OTQ and PQ parameters derived at 95% and 80% of the amplitude, named OTQ95, PQ95, OTQ80 and PQ80. Their Spearman's rank correlation coefficients were in the range of 0.73 to 0.77 (P < 0.001) indicating strong relationships with the visual ratings. The strengths of these correlations were similar to those found from inter-rater comparisons of visual evaluations of peak sharpness. ConclusionThe Open time percentage and Plateau quotients at 95% and 80% of the amplitude stood out as the possible candidates for capturing the sharpness of the lateral peaks with their reliability comparable to that of visual ratings.

A Newly Advanced Anti-Vibration Pad With a Phase Balancer Designed by Analysis of Washing Machine Behaviors

Abstract This study proposed an anti-vibration pad with a phase balancer that helps reduce wood floor vibrations from a washing machine as well as the vibrations of the machine itself. When a washing machine is installed just on anti-vibration pads, the floor vibrations can be reduced, but consequently the machine’s left–right vibrations become more violent. Accordingly, in order to identify the mechanism by which anti-vibration pads generate left-right vibrations in washing machines, the present study proposed a two-point measurement method that can determine vertical washing machine vibrations and phase differences. In addition, we proposed an optimal phase balancer designed by a finite element analysis-based response surface method for reducing vibrations using a phase difference. As a result, the anti-vibration pad with a phase balancer, when applied to washing machines, greatly contributed to simultaneously reducing the actual vibrations of washing machines and the vibration transfer to the floor.

Observed wintertime tidal and subtidal currents over the continental shelf in the northern South China Sea

AbstractSynthesis analyses were performed to examine characteristics of tidal and subtidal currents at eight mooring sites deployed over the northern South China Sea (NSCS) continental shelf in the 2006–2007 and 2009–2010 winters. Rotary spectra and harmonic analysis results showed that observed tidal currents in the NSCS were dominated by baroclinic diurnal tides with phases varying both vertically and horizontally. This feature was supported by the CC‐FVCOM results, which demonstrated that the diurnal tidal flow over this shelf was characterized by baroclinic Kelvin waves with vertical phase differences varying in different flow zones. The northeasterly wind‐induced southwestward flow prevailed over the NSCS shelf during winter, with episodic appearances of mesoscale eddies and a bottom‐intensified buoyancy‐driven slope water intrusion. The moored current records captured a warm‐core anticyclonic eddy, which originated from the southwestern coast of Taiwan and propagated southwestward along the slope consistent with a combination of β‐plane and topographic Rossby waves. The eddy was surface‐intensified with a swirl speed of &gt;50 cm/s and a vertical scale of ∼400 m. In absence of eddies and onshore deep slope water intrusion, the observed southwestward flow was highly coherent with the northeasterly wind stress. Observations did not support the existence of the permanent wintertime South China Sea Warm Current (SCSWC). The definition of SCSWC, which was based mainly on thermal wind calculations with assumed level of no motion at the bottom, needs to be interpreted with caution since the observed circulation over the NSCS shelf in winter included both barotropic and baroclinic components.

Note: Dynamic analysis of a robotic fish motion with a caudal fin with vertical phase differences

In this paper, a robotic fish with a caudal fin with vertical phase differences is studied, especially focusing on the energy consumption. Energies for thrusting a conventional robotic fish and one with caudal fin with vertical phase differences are obtained and compared each other. It is shown that a robotic fish with a caudal fin with vertical phase differences can save more energy, which implies the efficient thrusting via a vertically waving caudal fin.

Chest, head and whistle registers in an untrained female singer analyzed by videokymography, strobolaryngoscopy and sound spectrography

There has been a lack of objective data on the singing voice registers, particularly on the so called register, occurring in the top part of the female pitch range, which is accessible only to some singers. This study offers unique strobolaryngoscopic and high‐speed (7812.5 images/s) videokymographic data on the vocal fold behavior of an untrained female singer capable of producing three distinct voice qualities, i.e., the chest, head and whistle registers. The sound was documented spectrographically. The transition from chest to head register, accompanied by pitch jumps, occurred around tones B4‐C#5 (500‐550 Hz) and was found to be associated with a slight decrease in arytenoids adduction, resulting in decrease of the closed quotient. The register shifts from head to whistle, also accompanied by pitch jumps, occurred around tones E5‐B5 (670‐1000 Hz) without any noticeable changes in arytenoids adduction. Some evidence was found for the vocal tract influence on this transition. The mechanism of the vocal fold vibration in whistle register was found principally similar to that at lower registers: vibrations along the whole glottal length and vertical phase differences (indicated by sharp lateral peaks in videokymography) were seen on the vocal folds up to the highest tone G6 (1590 Hz).

Three registers in an untrained female singer analyzed by videokymography, strobolaryngoscopy and sound spectrography

There has been a lack of objective data on the singing voice registers, particularly on the so called "whistle" register, occurring in the top part of the female pitch range, which is accessible only to some singers. This study offers unique strobolaryngoscopic and high-speed (7812.5 imagess) videokymographic data on the vocal fold behavior of an untrained female singer capable of producing three distinct voice qualities, i.e., the chest, head and whistle registers. The sound was documented spectrographically. The transition from chest to head register, accompanied by pitch jumps, occurred around tones B4-C#5 (500-550 Hz) and was found to be associated with a slight decrease in arytenoids adduction, resulting in decrease of the closed quotient. The register shifts from head to whistle, also accompanied by pitch jumps, occurred around tones E5-B5 (670-1000 Hz) without any noticeable changes in arytenoids adduction. Some evidence was found for the vocal tract influence on this transition. The mechanism of the vocal fold vibration in whistle register was found principally similar to that at lower registers: vibrations along the whole glottal length and vertical phase differences (indicated by sharp lateral peaks in videokymography) were seen on the vocal folds up to the highest tone G6 (1590 Hz).

Aerodynamic study of three-dimensional larynx models using finite element methods

The airflow velocities and pressures are calculated from a three-dimensional model of the human larynx by using the finite element method. The laryngeal airflow is assumed to be incompressible, isothermal, steady, and created by fixed pressure drops. The influence of different laryngeal profiles (convergent, parallel, and divergent), glottal area, and dimensions of false vocal folds in the airflow are investigated. The results indicate that vertical and horizontal phase differences in the laryngeal tissue movements are influenced by the nonlinear pressure distribution across the glottal channel, and the glottal entrance shape influences the air pressure distribution inside the glottis. Additionally, the false vocal folds increase the glottal duct pressure drop by creating a new constricted channel in the larynx, and alter the airflow vortexes formed after the true vocal folds.

Simulation of vocal fold oscillation with a pseudo-one-mass physical model

This paper presents a novel “pseudo-one-mass model” of the vocal folds, which is derived from a previously proposed two-mass model. Two-mass models account for effects of vertical phase differences in fold motion by means of a pair of coupled oscillators that describe the lower and upper fold portions. Instead, the proposed model employs a single mass-spring oscillator to describe only the oscillation of the lower fold portion, while phase difference effects are simulated through an approximate phenomenological description of the upper glottal area. This approximate description is derived in the hypothesis that 1:1 modal entrainment occurs between the two masses in the large-amplitude oscillation regime, and is then exploited to derive the equations of the pseudo-one-mass model. Numerical simulations of a reference two-mass model are analyzed to show that the proposed approximation remains valid when values of the physical parameters are varied in a large region of the control space. The effects on the shape of the glottal flow pulse are also analyzed. Comparison of simulations with the reference two-mass model and the pseudo-one-mass model show that the dynamic behavior of the former is accurately approximated by the latter. The similarity of flow signals synthesized with the two models is assessed in terms of four acoustic parameters: fundamental frequency, maximum amplitude, open quotient, and speed quotient. The results confirm that the pseudo-one-mass model fit with good accuracy the behavior of the reference two-mass model, while requiring significantly lower computational resources and roughly half of the mechanical parameters.

A flow waveform-matched low-dimensional glottal model based on physical knowledge

The purpose of this study is to explore the possibility for physically based mathematical models of the voice source to accurately reproduce inverse filtered glottal volume-velocity waveforms. A low-dimensional, self-oscillating model of the glottal source with waveform-matching properties is proposed. The model relies on a lumped mechano-aerodynamic scheme loosely inspired by the one- and multimass lumped models. The vocal folds are represented by a single mechanical resonator and a propagation line which takes into account the vertical phase differences. The vocal-fold displacement is coupled to the glottal flow by means of an aerodynamic driving block which includes a general parametric nonlinear component. The principal characteristics of the flow-induced oscillations are retained, and the overall model is able to match inverse-filtered glottal flow signals. The method offers in principle the possibility of performing transformations of the glottal flow by acting on the physiologically based parameters of the model. This is a desirable property, e.g., for speech synthesis applications. The model was tested on a data set which included inverse-filtered glottal flow waveforms of different characteristics. The results demonstrate the possibility of reproducing natural speech waveforms with high accuracy, and of controlling important characteristics of the synthesis such as pitch.

The clinical usefulness of laryngeal videostroboscopy and the role of high-speed cinematography in laryngeal evaluation

Proper use of laryngeal videostroboscopy aids the otolaryngologist in appreciating vocal fold vibratory patterns and phonatory characteristics. A laryngology practice is incomplete without the application of the stroboscope in diagnosing and tracking treatment progression in patients with vocal complaints. Understanding both the mechanics and the principles of stroboscopy aids in understanding its utility in the diagnosis of laryngeal pathologic lesions. Videostroboscopic parameters evaluated during examination include symmetry, periodicity, glottic closure, amplitude, mucosal wave, and vertical phase differences. Published research has emphasized that videostroboscopic application improves diagnostic accuracy, as compared with traditional methods. High-speed laryngeal cinematography has mainly been a research tool over the years. Improvements in technology with digital imaging have brought it closer to clinical application, as it may have advantages over videostroboscopy in evaluating aperiodic vibratory patterns, visualization of onset and decay of vocalization, and in cases of diplo-or triplophonia.

A physically informed glottis model for real glottal flow wave form reproduction

A physically informed model of the glottal source is proposed. The model relies on a lumped mechanoaerodynamic scheme based on the mass-spring paradigm. The vocal folds are represented by a mechanical resonator plus a delay line which takes into account the vertical phase differences. The vocal fold displacement is coupled to the glottal flow by means of a nonlinear subsystem, based on a general parametric nonlinear model. The principal characteristics of the flow-induced oscillations are retained, and the overall model is suited for an identification approach where real (inverse filtered) glottal flow signals are to be reproduced. A data-driven identification procedure is outlined, where the parameters of the model are tuned in order to accurately match the target wave form. A nonlinear regression algorithm is used to train the nonlinear part. A set of inverse-filtered glottal flow wave forms with different pitch, open phase/closed phase ratio, and shape of the glottal wave form period, are used to test the effectiveness of the approach. The results demonstrate that the model can reproduce a wide range of target wave forms. Moreover, the flow wave forms generated by the trained model are characterized by spectral richness and are perceived as natural. [Work supported by EU.]

Diagnostics for propagating waves in the solar photosphere

view Abstract Citations (8) References (18) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Diagnostics for Propagating Waves in the Solar Photosphere Keil, Stephen L. ; Marmolino, Ciro Abstract The effects of pure acoustic waves of different frequencies on a number of Fe I lines formed in the photosphere are investigated. A dynamical model of the waves which considers velocity, temperature, and pressure fluctuations as functions of time is used to compute the line profiles. The extent to which the waves cause the lines to fluctuate, the time-averaged properties of the line profiles, and the measurability of vertical phase differences are all determined as functions of the frequency of the propagating wave. It is concluded that there is no intrinsic radiative limit, for frequencies of current observational interest, on ability to measure phase differences. The asymmetry induced by the propagation of acoustic waves in the photosphere is found to depend on the frequency of the waves. Acoustic waves contribute only marginally to line broadening. Publication: The Astrophysical Journal Pub Date: November 1986 DOI: 10.1086/164743 Bibcode: 1986ApJ...310..912K Keywords: Line Spectra; Photosphere; Solar Atmosphere; Solar Oscillations; Sound Waves; Wave Propagation; Audio Frequencies; Stellar Models; Time Dependence; Solar Physics; LINE PROFILES; SUN: ATMOSPHERE; SUN: OSCILLATIONS full text sources ADS |

Comments on the myoelastic - aerodynamic theory of phonation.

The myoelastic-aerodynamic theory of phonation has been quantified and tested with mathematical models. The models suggest that vocal fold oscillation is produced as a result of asymmetric forcing functions over closing and opening portions of the glottal cycle. For nearly uniform tissue displacements, as in falsetto voice, the asymmetry in the driving forces can result from the inertia of the air moving through the glottis. This inertia can in turn be enhanced or suppressed by supraglottal or subglottal vocal tract coupling. More obvious and pronounced asymmetries in the driving forces are associated with non-uniform vocal fold tissue displacements. These are combinations of normal tissue modes, and can result in vertical and horizontal phase differences along the surfaces, as observed in chest voice. The ranges of oscillation increase among various models as more freedom in the simulated tissue movement is incorporated. Of particular significance in initiating and maintaining oscillation are the vertical motions that facilitate coupling of aerodynamic energy into the tissues and allow tissue deformations under conditions of incompressibility. Vertical displacements also can have a significant on vocal tract excitation. Control of fundamental frequency of oscillation (FO) is basically myoelastic, partially as a result of deliberate or reflex adjustments of laryngeal muscles, and partially as a result of nonlinear tissue strain over the vibrational cycle. This places limits on the control of FO by subglottal pressure, and forces such control to be inseparably connected with vibrational amplitude, or less directly, with vocal intensity.

On the mechanics of vocal-fold vibration.

The human vocal fold is treated as a continuous, transversally isotropic, bounded medium. The theory of viscoelasticity is applied to formulate the stresses, strains, glottal tissue impedance, and propagation characteristics for sinusoidal oscillation within the vocal-fold tissues. Incompressibility of the tissues leads to a biharmonic differential equation, the solution of which represents commonly observed modes of vibration. The energy dissipated in the tissues and the associated damping factors are calculated. Mode impedances of the tissues are calculated and lumped-model approximations of the system evaluated. The usual mass-spring models are shown to be inadequate in certain important cases, especially during vocal-fold closure and for modes in which vertical phase differences occur. Subject Classification: [43]70.20.

Measurements of tidal-period winds in the 95- to 135-kilometer region

A method developed by G. V. Groves for the analysis of meteor winds has been used on chemical release wind data from rockets. Velocity amplitudes, phases, and amplitude errors for winds with periods of 8, 12, and 24 hours were computed in the 95- to 135-km region. An average wind, assumed to represent a constant prevailing wind was also computed in this altitude range. Vertical wavelengths and phase differences of the northward and eastward components of the prevailing and tidal winds are calculated and compared with recent results. Dissipative forces are also shown to be acting on the propagating diurnal and semidiurnal tides in the height range from 95 to 135 km.