An acoustic imaging metamaterial is provided for obtaining edge detection information of a tangible object. The acoustic imaging metamaterial includes a longitudinally extending phononic crystal substrate that defines a first major surface and a second major surface opposite the first major surface. A first structurally rigid grating layer is disposed adjacent the first major surface, and a second structurally rigid grating layer is disposed adjacent the second major surface. In various aspects, the first and second structurally rigid grating layers are identical in shape and dimensions, and are aligned with one another. The acoustic imaging metamaterial is configured to redirect, confine, and/or manipulate an incident acoustic wave resulting in a high contrast image used for extracting edge detection information of the tangible object. The background medium fluid of the system can be air or a fluid such as water.

Earplugs that have enhanced performance in protecting the user from high noise levels without impeding auditory awareness are described. The earplugs comprise a housing and a non-linear acoustic filter, wherein the non-linear acoustic filter can comprise a bulb. The earplugs are designed to be compatible with other types of headwear, e.g., headphones and helmets.

An acoustic structure for beaming soundwaves from a first direction toward a second direction, may include a plurality of phononic crystals. The plurality of phononic crystals have an outer border, an internal cavity and a channel extending between the outer border and the internal cavity, wherein the channel defines an opening within the outer border. The phononic crystals are disposed such that the opening faces the second direction. Soundwaves from the first direction are beamed to the second direction by the plurality of phononic crystals.

A vibration damping member mounted to an inside of a housing of an acoustic device includes a first member, a second member, and a third member. The first member and the second member are connected through the third member. The third member has a lower elastic modulus than the first member and the second member.

An electronic horn includes a cover (8) on a front side of an intermediate element (6). A first passage (P1) within the horn is defined by a central portion (82) of the cover (8) that projects into a cylindrical interior of a cylindrical water-proofing wall (621). Second passages (P2, P3, P4) extend generally concentrically with respect to the first passage (P1) and are respectively defined by water-proofing walls (83, 84) that are formed on the cover (8) and project into the interior spaces of water-proofing walls (622, 633). The outermost second passage (P4) opens toward the forward direction. The first and second passages (P1-P4) extend in a back-and-forth path that prevents any rainwater, which has entered the interior of the horn through the opening of the outermost second passage (P4), from reaching a resonance space (7) defined between the resonator (7) and a sound-generating oscillator (51).

Provided is an asymmetric three-dimensional lattice structure in which physical properties of a strut of a symmetric three-dimensional lattice structure is asymmetrically changed so as to adjust a band gap and a frequency range of a wave propagated in a particular direction in the three-dimensional lattice structure. An embodiment of the present disclosure also provides a lattice structure having six struts, four nodes, a first coating layer, and a second coating layer. The basic structure of the six struts is formed of polymer and the strut's basic structure has a same length L and radius r. Some struts may have a different thickness ratio between the first coating layer and the second coating layer, or may be coated with different materials to thereby have different properties.

Provided is an asymmetric three-dimensional lattice structure in which physical properties of a strut of a symmetric three-dimensional lattice structure is asymmetrically changed so as to adjust a band gap and a frequency range of a wave propagated in a particular direction in the three-dimensional lattice structure. An embodiment of the present disclosure also provides a lattice structure having six struts, four nodes, a first coating layer, and a second coating layer. The basic structure of the six struts is formed of polymer and the strut's basic structure has a same length L and radius r. Some struts may have a different thickness ratio between the first coating layer and the second coating layer, or may be coated with different materials to thereby have different properties.

The present invention relates to a noise reduction assembly for auscultation of a body. An embodiment of the assembly includes an auscultation device formed of a first material and having a proximal end for engagement with the body when the auscultation device is in an operative orientation. An interior dampening layer, which may be formed of a second material, is formed along an exterior surface of the auscultation device and covering all exterior surfaces thereof except the proximal end. An exterior dampening layer, which may be formed of a third material, is then formed in covering relations relative to the interior dampening layer.

The present invention relates to a noise reduction assembly for auscultation of a body. An embodiment of the assembly includes an auscultation device formed of a first material and having a proximal end for engagement with the body when the auscultation device is in an operative orientation. An interior dampening layer, which may be formed of a second material, is formed along an exterior surface of the auscultation device and covering all exterior surfaces thereof except the proximal end. An exterior dampening layer, which may be formed of a third material, is then formed in covering relations relative to the interior dampening layer.

Some embodiments are directed to an elementary acoustic metamaterial cell, including a body made of solid material and at least one resonator defining a groove of width l and depth p, the groove being open on the surface of the body, wherein the depth p is set by a resonant frequency (f) of the cell according to a relationship x, c being the speed of sound in air and the width l is set by an energy density confined in the cell according to a logarithmic relationship E.sub.max αlog (l) determined experimentally, the groove having an acoustic absorption controlled by a ratio between the depth p and the width l of the groove. Some embodiments are also directed to an acoustic screen including such an elementary cell.