The interrelationship of subglottic air pressure, fundamental frequency, and vocal intensity during speech

In this study we have simultaneously measured subglottic air pressure, airflow, and vocal intensity during speech in nine healthy subjects. Subglottic air pressure was measured directly by puncture of the cricothyroid membrane. The results show that the interaction between these aerodynamic properties is much more complex that previously believed. Certain trends were seen in most individuals, such as an increase in vocal intensity with increased subglottic air pressure. However, there was considerable variability in the overall aerodynamic properties between subjects and at different frequency and intensity ranges. At certain frequencies several subjects were able to generate significantly louder voices without a comparable increase in subglottic air pressure. We hypothesize that these increases in vocal efficiency are due to changes in vocal fold vibration properties. The relationship between fundamental frequency and subglottic pressure was also noted to vary depending on vocal intensity. Possible mechanisms for these behaviors are discussed.     

Effects of stimulation techniques on vocal responses: Implications for assessment and treatment

During voice evaluation and treatment it is customary for clinicians to elicit samples of the vowel /a/ from clients using various elicitation techniques. The purpose of this study was to compare the effects of four commonly used stimulation tasks on the laryngeal mechanism. Eleven female singing students, studying at a university music school, served as subjects for the study. The subjects phonated the vowel /a/ using 4 vocal stimulation techniques: yawn-sigh, gentle onset, focus, and the use of the voiceless fricative. Videoendoscopic and acoustic evaluations of their productions were done. Results show that, in the first 100 ms following the end of the formant transition, these techniques affected voice differently. The fundamental frequency was found to be highest in the yawn-sigh condition, whereas the maximum frequency perturbation was obtained for the voiceless fricative condition. Planned comparisons were made by comparing the data across 2 dimensions: (1) vowels elicited with voiced contexts versus those elicited with voiceless consonantal contexts and (2) vowels elicited with obstruent versus vowels elicited with nonobstruent consonantal contexts. Some changes in acoustic parameters brought about by these stimulation techniques may be explained on the basis of coarticulatory effects of the consonantal context.     

A reduced-order flow model for vocal fold vibration: From idealized to subject-specific models

We present a reduced-order model for fluid–structure interaction (FSI) simulation of vocal fold vibration during phonation. This model couples the three-dimensional (3D) tissue mechanics and a one-dimensional (1D) flow model that is derived from the momentum and mass conservation equations for the glottal airflow. The effects of glottal entrance and pressure loss in the glottis are incorporated in the flow model. We consider both idealized vocal fold geometries and subject-specific anatomical geometries segmented from the MRI images of rabbits. For the idealized vocal fold geometries, we compare the simulation results from the 1D/3D hybrid FSI model with those from the full 3D FSI simulation based on an immersed-boundary method. For the subject-specific geometries, we incorporate previously estimated tissue properties for individual samples and compare the results with those from the high-speed imaging experiment of in vivo phonation. In both setups, the comparison shows good agreement in the vibration frequency, amplitude, phase delay, and deformation pattern of the vocal fold, which suggests potential application of the present approach for future patient-specific modeling.     

Self‐assembly of a cadmium(II) diamondoid net with 2‐fold interpenetrating microporous structure

Assembly of 5‐methoxyisophthalic acid (H₂moip) with cadmium(II) ions in the presence of neutral ancillary 1,3‐bis(4‐pyridyl)propane (bpp) yields a new coordination polymer, [Cd(moip)(bpp)(H₂O)]_n·nH₂O ( 1 ). X‐ray single‐crystal diffraction determination reveals that complex 1 crystallizes in the space group C2/c of monoclinic crystal system: a = 14.545(2), b = 18.749(3), c = 17.359(3) Å, β = 105.480(2)º. Complex 1 is a 4‐connected 3D diamondoid topological framework with a 2‐fold interpenetration. Interestingly, the dense adamantine cages with inherent microporous structure are filled with free water molecules to further stabilize the coordination network.     

Models of Adjacent Re‐Entry Folds in the β Form of Syndiotactic Polystyrene. Conformational and Packing Analysis by Molecular Mechanics

The adjacent re‐entry folds of chains of syndiotactic polystyrene crystallized in the β form have been investigated by molecular mechanics. Various models of fold of chains along bilayers have been found. The results are in agreement with the literature experimental data indicating that the fold surface is irregular. Both the conformational and the packing energy of folded chains have been minimized by various techniques using several set of potential functions. A theoretical prediction of the work of fold is given.