Variable acoustic properties can be obtained at the diaphragm of an electroacoustic transducer, with the help of very basic control strategies, among which is the simple electrical shunting of the transducer. These shunt techniques are compared to active feedback techniques for controlling the acoustic impedance of an electroacoustic transducer. It is shown here that the formulation of feedback...

We quantify the sensitivity of turbine acoustic impedance to aerodynamic design parameters. Impedance boundary conditions are an influential yet uncertain parameter in predicting thermoacoustic stability gas combustors. extend semi-actuator disk model cambered blades, using non-linear time-domain computations vane and stage cascades with forcing for validation data. Discretising aerofoils into ...

Reflection of sound waves, due to acoustic impedance mismatch at the interface of two media, is the principal physical property which allows visualization with ultrasound. In this paper, we investigate reconstruction of the acoustic impedance from ultrasound images for the first time. Similar to spatial compounding, we combine multiple images to improve the estimation. We use phase information ...

The acoustic coupling between the voice production system and the vocal tract has a significant influence on the production of voice. In this study, the coupling effect was represented using the acoustic pressure difference across the glottis, which is capable of inducing a flow, and the mean acoustic pressure in the glottis, which acts as a driving force for the vocal folds. These specific aco...

A big challenge in studying organic rich shale is to predict its kerogen content and maturity from indirect observations. Kerogen maturation changes shale texture; for example, it generates microcracks and fractures in the matrix. Assessment of maturity from indirect measurements can be greatly enhanced by exploiting any existing correlations between physical properties, microstructure, and ker...

Measurements of middle ear (ME) acoustic power flow (power reflectance, power absorption, and transmittance) and normalized impedance (acoustic resistance, acoustic reactance, and impedance magnitude) were compared for their utility in clinical applications. Transmittance, a measure of the acoustic power absorbed by the ME, was found to have several important advantages over other measures of a...