Airborne acoustic absorbers include periodic arrays of Helmholtz resonators that are covered and/or partially filled with an acoustically absorptive material, such as a thermoplastic foam. The combined structures have much broader frequency ranges of high acoustic absorption than do structures having only Helmholtz resonators or acoustically absorbing foam.

Disclosed herein are implementations of acoustic metamaterial structures and geometric configurations of acoustic metamaterial structures which produce sound amplification or cancellation. An acoustic metamaterial device for using with a sound source includes a plurality of fins, where each fin is made from a very dense material with respect to air which creates the anisotropic properties of the acoustic metamaterial device, where each fin has a length dimension, a width dimension, and a thickness dimension, the width and length dimension being equal and substantially perpendicular to the direction of sound wave propagation from the sound source, where each fin is sized different from other fins along the width and length dimension, and where the plurality of fins are interconnected such that planes formed by the width and length dimension of each fin faces perpendicular to the sound wave propagation direction from the sound source.

Disclosed herein are implementations of acoustic metamaterial structures and geometric configurations of acoustic metamaterial structures which produce sound amplification or cancellation. An acoustic metamaterial device for using with a sound source includes a plurality of fins, where each fin is made from a very dense material with respect to air which creates the anisotropic properties of the acoustic metamaterial device, where each fin has a length dimension, a width dimension, and a thickness dimension, the width and length dimension being equal and substantially perpendicular to the direction of sound wave propagation from the sound source, where each fin is sized different from other fins along the width and length dimension, and where the plurality of fins are interconnected such that planes formed by the width and length dimension of each fin faces perpendicular to the sound wave propagation direction from the sound source.

An exhaust muffler has an outer cylinder into which an exhaust gas from an engine is introduced and a muffling member made of a foamed ceramic material. The outer cylinder has an inner cylinder through which the exhaust gas passes, a part of the muffling member is supported by an outer wall of the inner cylinder via a holding member. The inner cylinder includes, in an area where the inner cylinder overlaps with the muffling member with respect to axial direction of the inner cylinder, a porous wall portion formed with communication holes communicating an inside and an outside of the inner cylinder. The holding member is arranged at a position where it does not overlap with a part of the porous wall portion, so that muffling effect is enhanced, and the muffling member having a low resistance to impact forces can be supported stably by the inner cylinder.

Devices for preventing unintended conversation from being recorded by a voice activated assistant device/application (VAD) are disclosed. The device is contoured to fit over a functional surface of a VAD that typically includes a plurality of microphones and control buttons. The device covers the microphones and uses its own microphones to monitor for an authorization input signal. In an embodiment, the devices uses speakers aligned with and opposing each VAD microphone. The device emits interfering audible signals during this mode of operation. Once the device senses an authorization input, the device decouples its speakers from the interfering audible signal and instead allows the device microphones to pass through to the VAD. During this mode, the VAD is in normal operation.

Provided is a sound-absorbing material, including an adsorbent material and a thermal conductive material. The thermal conductive material is uniformly dispersed in the sound-absorbing material. The thermal conductive material includes a carbon fiber material, and a weight ratio of the carbon fiber material in the sound-absorbing material is within a range of 0.05% to 10%. Further provided are a preparation method of the sound-absorbing material and a speaker using the sound-absorbing material. The sound-absorbing material has higher thermal conductivity and can be added to a rear cavity of the speaker to effectively conduct heat generated when the speaker is working, thereby improving the heat dissipation performance of the speaker.

Provided is a sound-absorbing material, including an adsorbent material and a thermal conductive material. The thermal conductive material is uniformly dispersed in the sound-absorbing material. The thermal conductive material includes a carbon fiber material, and a weight ratio of the carbon fiber material in the sound-absorbing material is within a range of 0.05% to 10%. Further provided are a preparation method of the sound-absorbing material and a speaker using the sound-absorbing material. The sound-absorbing material has higher thermal conductivity and can be added to a rear cavity of the speaker to effectively conduct heat generated when the speaker is working, thereby improving the heat dissipation performance of the speaker.

A method of designing an acoustic liner includes identifying acoustic path lengths that will attenuate a frequency within a frequency range of interest, and selecting a liner configuration with a combination of acoustic paths that addresses the frequency range of interest. The selection may be made after a comparison of the response of different liner configurations.

A method of designing an acoustic liner includes identifying acoustic path lengths that will attenuate a frequency within a frequency range of interest, and selecting a liner configuration with a combination of acoustic paths that addresses the frequency range of interest. The selection may be made after a comparison of the response of different liner configurations.

The present disclosure relates to a telepresence system capable of providing telepresence in a better acoustic environment. The telepresence system includes: a network that connects a plurality of bases; and a plurality of telepresence facilities that transmit and receive video images and sound via the network, and share the video images and the audio between the respective bases. Each telepresence facility is then entirely covered with a sound shielding portion that acoustically shields the external environment and the internal environment of the telepresence facility from each other. Further, in each of the telepresence facilities, the same sound field as that of another telepresence facility is reproduced in a closed space shielded by the sound shielding portion. The present technology can be applied to a telepresence system capable of making a user feel as if places were connected and the other party were present in the same place, for example.