In this study, aerodynamic and acoustic measurements were obtained in a dynamic mechanical model of the larynx and vocal tract. The model consisted of a uniform duct, intersected by a pair of sinusoidally oscillating shutters. A controlled airflow along the duct was periodically disturbed by the action of the shutters and pressure, and flow velocity measurements were obtained in the region down...

Condensation of atoms from the vapor into a third sound resonance is expected to be capable of acoustic amplification. This results from normal to superfluid conversion that coherently accommodates atoms into the third sound velocity field. Consideration of third sound in light of the equilibrium detailed balance between vapor particles and the superfluid film provides further evidence that aco...

This article focuses on the hydration, and associated microstructure development, of b-hemihydrate to dihydrate (gypsum). The sound velocity is used to quantify the composition of the fresh slurry as well as the hardening and hardened—porous—material. Furthermore, an overview of available hydration kinetic and volumetric models for gypsum is addressed. The presented models predict the sound vel...

Techniques for the use of audio-frequency sound waves in the measurement of flow rate and particle size and the estimation of the volume of material contained in partially closed vessels are described and discussed. INTRODUCTION Non-invasive interrogation of systems and processes involving dry particulate materials is particularly challenging. X-rays and γ-rays, for example, offer the prospect ...

BACKGROUND Male parasitic wasps attract females with a courtship song produced by rapid wing fanning. Songs have been described for several parasitic wasp species; however, beyond association with wing fanning, the mechanism of sound generation has not been examined. We characterized the male courtship song of Cotesia congregata (Hymenoptera: Braconidae) and investigated the biomechanics of sou...

In this article the sound velocity through a mix is correlated to the hydration degree of the mix. Models are presented predicting the sound velocity through fresh slurries and hardened products. These two states correspond to the starting and finishing point of the hydration process. The present research shows that a linear relation between the amount of hydration-product (gypsum) formed (Smit...

2014 Resonant scattering of sound by finite physical structures is considered as a possible means of producing bistability in diffusion of sound waves. Nonlinear dependence of the sound propagation velocity upon the sound intensity is needed in order to provide proper conditions for the insurgence of bistability. Multistability behaviour is considered as a possibility in the concurrence of prop...

An early diastolic sound in a patient with apical left ventricular disease is reported. Pulsed Doppler echocardiography showed blood flow within the left ventricular cavity during the isovolumic relaxation period whose peak flow velocity was synchronous with the onset of this diastolic sound. Because it occurred before filling started it could not have been either a third or fourth heart sound....

It is a deceptively simple question to ask how acoustic disturbances propagate in a non–homogeneous flowing fluid. If the fluid is barotropic and inviscid, and the flow is irrotational (though it may have an arbitrary time dependence), then the equation of motion for the velocity potential describing a sound wave can be put in the (3+ 1)–dimensional form ∆ψ ≡ ∂μ ( √−g g ∂νψ) / √−g = 0. The acou...

The interference of the direct wave from the point source to the receiver and the wave reflected from the impedance ground in a turbulent atmosphere is studied. A parabolic equation approach for calculating the sound pressure p at the receiver is formulated. Then, the parabolic equation is solved by the Rytov method yielding expressions for the complex phases of direct and ground-reflected wave...