Acoustic modeling of three-dimensional-printed fibrous sound absorbersa).

In this study, an analytical model was developed to predict the sound absorption performance of fibrous absorbers fabricated using an extrusion-based three-dimensional (3D) printing method. The proposed model employs geometric design parameters, including the average fiber diameter and the horizontal and vertical fiber separations, to calculate the porosity, static airflow resistivity, tortuosity, and viscous and thermal characteristic lengths. These transport parameters are then used within the Johnson-Champoux-Allard semiempirical formulation to predict the normal incidence sound absorption coefficient.

Flexible Piezoelectric Nanocolumnar Composite Films as Flat-Panel Loudspeakers: Application and Modeling.

Highly anisotropic piezoelectric composites promise to progress electroacoustic devices as a class by combining the advantages of both piezoceramics and polymers. Fundamentally, piezoelectric loudspeakers employ the converse piezoelectric effect to convert electrical to mechanical energy. Quasi-1-3 piezoceramic/polymer composites enable flat-panel loudspeakers that are tunable in elastic modulus, with opportunities for mechanical flexibility, optical transparency, and large-area coverage.

An iterative transfer matrix approach for estimating the sound speed and attenuation constant of air in a standing wave tube.

In this work, an iterative method based on the four-microphone transfer matrix approach was developed for evaluating the sound speed and attenuation constant of air within a standing wave tube. When the air inside the standing wave tube is treated as the material under test, i.e.