Active control of membrane-type acoustic metamaterial

A method for sound attenuation comprising:

• providing a panel comprising a substantially acoustically transparent, rigid frame with a planar geometry divided into a plurality of individual cells with a first electromagnetic or electrostatic response unit for at least a plurality of the individual cells the planar geometry of each individual cell, the flexibility of a flexible material and a respective weight thereon establishing a base resonant frequency of the sound attenuation;
• actuating the electromagnetic or electrostatic response units to control the frequency response of the individual cells for attenuating sound;
• and
• the electromagnetic or electrostatic response units modifying the resonant frequency of the individual cell by using a pair of non-planar electrodes maintained at different electric potential to apply a non-uniform electric field to a central weight.

A sound attenuation panel comprising:

• a substantially acoustically transparent, rigid frame with a planar geometry divided into a plurality of individual cells configured for attenuating sound;
• a sheet of a flexible material fixed to the rigid frame;
• each individual cell having a weight fixed to a membrane;
• the planar geometry of each individual cell, a flexibility of the flexible material and the respective weight thereon establishing a base resonant frequency of the sound attenuation;
• at least a plurality of the individual cells having a first electromagnetic or electrostatic response unit configured to modify a resonant frequency of the individual cell;
• and
• the first electromagnetic or electrostatic response units modifying the resonant frequency of the cell by using a pair of non-planar electrodes maintained at different electric potential to apply a non-uniform electric field, wherein
• the non-uniform electric field comprises an electromagnetic field generated across a central weight comprising selected from the group consisting of a dielectric substance or a ferromagnetic substance.

A sound attenuation panel comprising:

• a substantially acoustically transparent, rigid frame with a planar geometry divided into a plurality of individual cells configured for attenuating sound;
• a sheet of a flexible material fixed to the rigid frame;
• each individual cell having a weight fixed to a membrane;
• the planar geometry of each individual cell, a flexibility of the flexible material and the respective weight thereon establishing a base resonant frequency of the sound attenuation;
• at least a plurality of the individual cells having a first electromagnetic or electrostatic response unit configured to modify a resonant frequency of the individual cell;
• and
• the first electromagnetic or electrostatic response units modifying the resonant frequency by using a central weight made of a permanent magnetic substance and a non-uniform magnetic field generated by an electric current coil.

A sound attenuation panel comprising:

• a substantially acoustically transparent, rigid frame with a planar geometry divided into a plurality of individual cells configured for attenuating sound;
• a sheet of a flexible material fixed to the rigid frame;
• each individual cell having a weight fixed to a membrane;
• the planar geometry of each individual cell, a flexibility of the flexible material and the respective weight thereon establishing a base resonant frequency of the sound attenuation;
• at least a plurality of the individual cells having a first electromagnetic or electrostatic response unit configured to modify a resonant frequency of the individual cell;
• a center platelet mounted to the sheet of flexible material, the sheet of flexible material and establishing the resonant frequency of the cell;
• and
• one of the electrodes forming at least a portion of the center platelet, and a second one of the electrodes provided separately from the center platelet and having a physical separation from the center weight, in a direction transverse to the sheet of flexible material.

A sound attenuation panel comprising:

• a substantially acoustically transparent planar, rigid frame divided into a plurality of individual cells configured for attenuating sound;
• a sheet of a flexible material fixed to the rigid frame;
• a center platelet mounted to the sheet of flexible material, the sheet of flexible material and the center platelet establishing a resonant frequency of the cell;
• and
• at least a plurality of the individual cells having a non-uniform electric field generated by a pair of electrodes maintained at different electric potential, a first one of the electrodes forming at least a portion of the center platelet, and a second one of the electrodes provided separately from the center platelet and having a physical separation from the center weight, in a direction transverse to the sheet of flexible material, the electrodes configured to modify the resonant frequency of the individual cell in response to the different electric potential.

A sound attenuation panel comprising:

• a substantially acoustically transparent, rigid frame with a planar geometry divided into a plurality of individual cells configured for attenuating sound;
• a sheet of a flexible material with a mass fixed to the rigid frame;
• the planar geometry of each individual cell, the flexibility of the flexible material and the mass of the material suspended by the rigid frame establishing a base resonant frequency of the sound attenuation;
• at least a plurality of the individual cells having a first electrode formed of an electric coating on the sheet of flexible material;
• the plurality of cells having a second electrode fixed to the sheet of flexible material with a dielectric separation from the first electrode;
• at least one of the electrodes formed as a conductive mesh;
• and
• the plurality of the cells having a non-uniform electric field generated by a pair of electrodes maintained at different electric potential, the electrodes configured to modify the resonant frequency of the cell in response to the different electric potential.