Influence of geometry on acoustic end-corrections of slits in microslit absorbers.

The acoustic behavior of individual slits within microslit absorbers (MSAs) is investigated to explore the influence of porosity, edge geometry, slit position, and plate thickness. MSAs are plates with arrays of slit-shaped perforations, with the height of the order of the acoustic viscous boundary layer thickness, for optimized viscous dissipation. Due to hydrodynamic interaction, each slit behaves as confined in a rectangular channel.

The influence of edge geometry on end-correction coefficients in micro perforated plates.

Global expressions are proposed for end-correction coefficients in micro perforated plates (MPPs) using non-dimensional parameters. MPPs are sound absorbers with small perforation diameters such that the Stokes boundary layers fill up almost the entire perforation. Sound absorption does not only occur within the perforation, but also takes place just outside of it.

Comments on the low frequency radiation impedance of a duct exhausting a hot gas.

The influence of convection and temperature on the radiation impedance of an open duct termination exhausting a hot gas is commonly described by a complex theory. A simplified analytical expression is proposed for low frequencies. Both models assume a free jet with uniform velocity bounded by infinitely thin shear layers.

Comments on "A theoretical model of the pressure field arising from asymmetric intraglottal flows applied to a two-mass model of the vocal folds" [J. Acoust. Soc. Am. 130, 389-403 (2011)].

After demonstrating by means of an in vitro model experiment that the flow in the glottis can become asymmetric, Erath et al. [J. Acoust.

Aeroacoustics of the swinging corrugated tube: voice of the Dragon.

When one swings a short corrugated pipe segment around one's head, it produces a musically interesting whistling sound. As a musical toy it is called a "Hummer" and as a musical instrument, the "Voice of the Dragon." The fluid dynamics aspects of the instrument are addressed, corresponding to the sound generation mechanism.

An in vitro setup to test the relevance and the accuracy of low-order vocal folds models.

An experimental setup and human vocal folds replica able to produce self-sustained oscillations are presented. The aim of the setup is to assess the relevance and the accuracy of theoretical vocal folds models. The applied reduced mechanical models are a variation of the classical two-mass model, and a simplification inspired on the delayed mass model for which the coupling between the masses is expressed as a fixed time delay.