Abstract: A sound absorbing metamaterial comprises an acoustic impedance-matched surface configured to minimize reflection from an incident acoustic wave. The surface is comprised of an elastic or flexible membrane and a substantially rigid mass mounted on the membrane. A relatively solid surface is provided as a reflective surface and is positioned behind the membrane. The reflective surface is separated by a predetermined distance from the elastic or flexible membrane and forms a fluid space between the membrane and the solid surface. The mass mounted on the membrane, in combination with the elastic membrane establish a plurality of eigenfrequencies.

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.

Abstract: A substantially acoustically transparent planar, rigid frame divided into a plurality of individual, substantially two-dimensional cells is used to construct a sound absorption panel. A sheet of a flexible material is fixed to the rigid frame, and a plurality of platelets fixed to the sheet of flexible material such that each cell is provided with a respective platelet, thereby establishing a resonant frequency, establishing an increase in an absorption coefficient of the panel. The flexible material has a wrinkle or corrugation to permit distortion with reduced material elasticity. The wrinkle or corrugation permits the flexible material to distort beyond that afforded by a planar material of the same type, while retaining mechanical strength in supporting the plurality of platelets.

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.

Abstract: A substantially acoustically transparent planar, rigid frame divided into a plurality of individual, substantially two-dimensional cells is used to construct a sound absorption panel. A sheet of a flexible material is fixed to the rigid frame, and a plurality of platelets fixed to the sheet of flexible material such that each cell is provided with a respective platelet, thereby establishing a resonant frequency, establishing an increase in an absorption coefficient of the panel. The flexible material has a wrinkle or corrugation to permit distortion with reduced material elasticity. The wrinkle or corrugation permits the flexible material to distort beyond that afforded by a planar material of the same type, while retaining mechanical strength in supporting the plurality of platelets.

Abstract: A sound absorbing metamaterial comprises an acoustic impedance-matched surface configured to minimize reflection from an incident acoustic wave. The surface is comprised of an elastic or flexible membrane and a substantially rigid mass mounted on the membrane. A relatively solid surface is provided as a reflective surface and is positioned behind the membrane. The reflective surface is separated by a predetermined distance from the elastic or flexible membrane and forms a fluid space between the membrane and the solid surface. The mass mounted on the membrane, in combination with the elastic membrane establish a plurality of eigenfrequencies.

Abstract: An acoustic/vibrational energy absorption metamaterial includes at least one enclosed planar frame with an elastic membrane attached having one or more rigid plates are attached. The rigid plates have asymmetric shapes, with a substantially straight edge at the attachment to said elastic membrane, so that the rigid plate establishes a cell having a predetermined mass. Vibrational motions of the structure contain a number of resonant modes with tunable resonant frequencies.

Abstract: An acoustic/vibrational energy absorption metamaterial includes at least one enclosed planar frame with an elastic membrane attached having one or more rigid plates are attached. The rigid plates have asymmetric shapes, with a substantially straight edge at the attachment to said elastic membrane, so that the rigid plate establishes a cell having a predetermined mass. Vibrational motions of the structure contain a number of resonant modes with tunable resonant frequencies.