An acoustic absorbing filler, the acoustic absorbing filler comprising agglomerates comprising a first phase comprising a plurality of porous particulates and a second phase comprising a binder; wherein the acoustic absorbing filler has a median sieved particle size of from 100 micrometer to 700 micrometers and a specific surface area of from 50 m.sup.2/g to 900 m.sup.2/g; wherein the acoustic absorbing filler has a normal incidence acoustic absorption of no less than 0.20 alpha at 400 Hz.

A composite coating material for passive vibration damping is provided. The composite coating material includes a polymer matrix, and a piezoelectric ceramic filler and an electrically conductive filler dispersed in the polymer matrix. Particles of the piezoelectric ceramic filler have an average particle size of greater than about 100 microns (μm).

A composite coating material for passive vibration damping is provided. The composite coating material includes a polymer matrix, and a piezoelectric ceramic filler and an electrically conductive filler dispersed in the polymer matrix. Particles of the piezoelectric ceramic filler have an average particle size of greater than about 100 microns (μm).

An acoustic absorbing filler, the acoustic absorbing filler comprising a core particle comprising a polymer; an outer layer coated on the core particle, wherein the outer layer comprise microporous particulates; and wherein the acoustic absorbing filler has a median particle size of from 100 micrometer to 700 micrometers and a specific surface area of from 10 m.sup.2/g to 400 m.sup.2/g; wherein the acoustic absorbing filler has a normal incidence acoustic absorption of no less than 0.15 at 300 Hz when measured in a 20 mm packed bed.

Various metamaterials are disclosed. An example metamaterial comprises: a first portion with a plurality of nanoparticles; a second portion with a plurality of molecules configured to interlink with the plurality of nanoparticles; and a signal generator configured to provide a signal to the material. The first portion and the second portion of the material are configured to form a hybrid molecule-nanoparticle super-lattice. In some implementations, the first portion of the material is configured to have a mass configured to achieve, at least in part, a designated resonance frequency. The second portion of the material is, in some implementations, configured to have a molecular stiffness configured to achieve, at least in part, the designated resonance frequency. The signal generator is, in some implementations, configured to generate radio frequency (RF) signals.

An ultrasound apparatus includes an ultrasound transducer array configured to transmit and receive ultrasound signals and an acoustic lens that includes signal-attenuating particles in a polymer matrix configured to provide signal attenuation and impedance matching for the ultrasound signals. The acoustic lens is disposed over a first surface of the ultrasound transducer array. The signal-attenuating particles include PEBAX.

An ultrasound apparatus includes an ultrasound transducer array configured to transmit and receive ultrasound signals and an acoustic lens that includes signal-attenuating particles in a polymer matrix configured to provide signal attenuation and impedance matching for the ultrasound signals. The acoustic lens is disposed over a first surface of the ultrasound transducer array. The signal-attenuating particles include PEBAX.

The present disclosure provides a method for producing a metal structure having holes dispersed in a matrix and having inorganic particles disposed inside the holes, that are capable of moving in the holes independently of the matrix, the method making it possible to increase the proportion of inorganic particles in the metal structure that are capable of moving in the holes independently of the matrix. In the method for producing a metal structure whereby inorganic particles are disposed inside holes dispersed in a matrix so as to be capable of moving independently of the matrix, the hollow particles covering the inorganic particles which are distributed in the matrix of the metal structure are fragmented so that the inorganic particles are disposed inside the holes formed by fragmenting the hollow particles.

The present disclosure provides a method for producing a metal structure having holes dispersed in a matrix and having inorganic particles disposed inside the holes, that are capable of moving in the holes independently of the matrix, the method making it possible to increase the proportion of inorganic particles in the metal structure that are capable of moving in the holes independently of the matrix. In the method for producing a metal structure whereby inorganic particles are disposed inside holes dispersed in a matrix so as to be capable of moving independently of the matrix, the hollow particles covering the inorganic particles which are distributed in the matrix of the metal structure are fragmented so that the inorganic particles are disposed inside the holes formed by fragmenting the hollow particles.

The disclosure relates to acoustic panels and methods for preparing them. The disclosure relates more particularly to panels having a porous facing and to methods for making such panels. One aspect of the disclosure is an acoustic panel comprising a base structure. The base structure has one or more edges, an outward major surface having a total area, and an inward major surface opposing the outward major surface. The base structure has a noise reduction coefficient (NRC) of at least about 0.3. The panel includes a coating layer directly disposed on the outward major surface of the base structure, the coating layer being formed of an open-cell foam. The coating layer has an exterior major surface opposing the outward major surface of the base structure. The coating layer is substantially scattering for light in the wavelength range of 380 nm to 780 nm, and has an absorption coefficient of less than 0.5 for acoustic frequencies in the range of 100 Hz to 10,000 Hz.