TECHNOLOGICAL PROCESS OF SOUND-ABSORBING PANELS

Optimised sound absorbing panels with quarter-wave resonators

The viscothermal wave propagation of the air inside the resonators is efficiently described by the so-called low reduced frequency model. Using this model, absorption coefficients can be calculated for different configurations. The theory has been implemented together with an optimisation algorithm, so that the dimensions of the resonators can be optimised to satisfy any desired absorption leve...

Sound Image Localization on Flat Display Panels

A sound absorbing metasurface with coupled resonators

An impedance matched surface is able, in principle, to totally absorb the incident sound and yield no reflection, and this is desired in many acoustic applications. Here we demonstrate a design of impedance matched sound absorbing surface with a simple construction. By coupling different resonators and generating a hybrid resonance mode, we designed and fabricated a metasurface that is impedanc...

On measurement of mechanical properties of sound absorbing materials

This paper is an overview of quasistatic measurement technique used to determine mechanical properties of sound absorbing materials. Experimental context and behaviour of polymer foam and rock wool are summarized. Concerning parameters are: static and dynamic strains, dynamic effects such as skeleton resonance and coupling with saturating fluid. Material anisotropy and frequency dependance of c...

The directivity of the sound radiation from panels and openings.

This paper presents a method for calculating the directivity of the radiation of sound from a panel or opening, whose vibration is forced by the incidence of sound from the other side. The directivity of the radiation depends on the angular distribution of the incident sound energy in the room or duct in whose wall or end the panel or opening occurs. The angular distribution of the incident sou...