Active control of membrane-type acoustic metamaterial

Patent metadata

Field	Value
Publication number	US-9659557-B2
Application number	US-201415022456-A
Country	US
Kind code	B2
Filing date	Sep 19, 2014
Priority date	Sep 19, 2013
Publication date	May 23, 2017
Grant date	May 23, 2017

Abstract

Sound attenuation is performed using a sound attenuation panel using an electromagnetic or electrostatic response unit to modify resonance. The sound attenuation panel has an acoustically transparent planar, rigid frame divided into a plurality of individual cells configured for attenuating sound. In one configuration, each cell has a weight fixed to the membrane. The planar geometry of each said individual cell, the flexibility of the membrane, and the weight establish a base resonant frequency for sound attenuation. The electromagnetic or electrostatic response unit is configured to modify the resonant frequency of the cell.

First claim

What is claimed is:

1. 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; and
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, wherein the central weight has a disk shape polarized by she electric field to form an electric dipole.

2. The sound attenuation panel of claim 1 , further comprising:
the modified resonant frequency by at least a plurality of the cells having a non-uniform electric field generated by a pair of electrodes maintained at different electric potential with a central weight made of either dielectric or metallic substance, or by a non-uniform magnetic field generated by an electric current coil with a central weight made of a ferromagnetic substance.

3. The sound attenuation panel of claim 1 , further comprising the cells having a generally two-dimensional structure.

4. The sound attenuation panel of claim 1 , further comprising:
a feedback circuit connected to the first electromagnetic or electrostatic response unit;
the feedback circuit connected to the first electromagnetic or electrostatic response unit, thereby sensing acoustic vibrations or waves and providing information concerning the acoustic vibration or waves for external detection of the presence of acoustic sources; and
an output circuit, responsive to the feedback circuit, for adjusting the resonant frequency of the sound attenuation structure.

5. The sound attenuation panel of claim 1 , further comprising:
a central platelet supported by the sheet of flexible material;
a first electrode positioned on one side of the central platelet; and
a second electrode positioned on an opposite side of the central platelet in an opposing relationship with the first electrode, wherein an electric voltage between the first and second electrodes establishes an electrostatic field across the sheet of flexible material and the central platelet in accordance with a distance between the first and second electrodes as established by the thickness of the central platelet, wherein
the cell without voltage applied between the first and second electrodes has a predetermined resonant frequency, and a voltage applied between the electrodes results in additional support for the membrane, thereby increasing the resonant frequency of the cell.

6. The sound attenuation panel of claim 5 , further comprising:
the first electrode comprising a conductive film coated on at least one of the membrane and the platelet;
the second electrode comprising a conductive mesh positioned against at least one of the membrane and the platelet; and
at least one of the first and second electrodes operatively connected to a connection electrode.

7. The sound attenuation panel of claim 1 , further comprising:
a first electrode positioned on one side of the sheet of flexible material; and
a second electrode positioned on an opposite side of the sheet of flexible material in an opposing relationship with the first electrode, wherein an electric voltage between the first and second electrodes establishes an electrostatic field across the sheet of flexible material in accordance with a distance between the first and second electrodes as established by the thickness of the sheet of flexible material, wherein
the cell without voltage applied between the first and second electrodes has a predetermined resonant frequency, and a voltage applied between the electrodes results in additional support for the membrane, thereby increasing the resonant frequency of the cell.

8. The sound attenuation panel of claim 7 , further comprising:
the first electrode comprising a conductive film coated on the membrane;
the second electrode comprising a conductive mesh positioned against the membrane; and
at least one of the first and second electrodes operatively connected to a connection electrode.

9. The sound attenuation panel of claim 1 , further comprising:
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 to a central weight.

10. The sound attenuation panel of claim 1 , further comprising:
at least one of the cells having a second electromagnetic or electrostatic response unit, with the first electromagnetic or electrostatic response unit and the second electromagnetic or electrostatic response unit placed together as one combined unit, with a first unit of the combined unit serving as detector of incoming sound, and a second unit of the combined unit serving to emit waves with a right amplitude and a right phase, the combined unit permitting attenuation of outgoing waves selectively in reflection and in transmission.

11. The sound attenuation panel of claim 1 , further comprising:
at least one of the cells having a second electromagnetic or electrostatic response unit, with the first electromagnetic or electrostatic response unit and the second electromagnetic or electrostatic response unit placed together as one combined unit, with a first unit of the combined unit serving as detector of incoming sound, and a second unit of the combined unit serving to emit waves with a right amplitude and a right phase, the combined unit permitting attenuation of outgoing waves either in reflection or in transmission.

12. The sound attenuation panel of claim 1 , further comprising:
at least a plurality of the 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; 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.

13. The sound attenuation panel of claim 12 , further comprising:
each cell having a platelet fixed to the membrane; and
the planar geometry of each individual cell, the flexibility of the flexible material and a mass of the material, including the weight of the platelet establishing the base resonant frequency of the sound attenuation.

14. The sound attenuation panel of claim 1 , further comprising:
the first electromagnetic or electrostatic response units modifying the resonant frequency of the cell by using a pair of electrodes maintained applying electric potentials to the weight fixed to a membrane; and
at least one of the electrodes formed as a conductive mesh.

15. A method for sound attenuation comprising:
providing the panel of claim 1 ; and
actuating the electromagnetic or electrostatic response units to control the frequency response of the individual cells for attenuating sound.

16. 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 electro

Assignees

• Univ Hong Kong Science & Tech

Inventors

• Yang Zhiyu
• Sheng Ping
• Yang Min
• Tang Suet To
• Ma Guancong
• Xiao Songwen

Classifications

• G10K2210/3212

  Actuator details, e.g. composition or microstructure · CPC title

• G10K11/172 Primary

  using resonance effects · CPC title

• G10K2210/32271

  Active resonators · CPC title

• G10K11/1788

  Physics · mapped topic

• G10K11/1782

  Physics · mapped topic