An acoustic metamaterial structure acts as a sound reducing filter in that the level of sound that exits the structure is much less than the magnitude of sound that enters the structure. In forming the structure, modular stages of a given geometry are stacked upon one another to create a cell. Each stage of the cell is provided with a nozzle that is acoustically connected to the nozzles of other stages of the cell. The stages have chambers that are positioned radially or laterally outside of the respective nozzles, with the chambers of the cell being acoustically connected to one another. An amalgamation of cells are arranged in an adjacent formation, with chambers of the cells being acoustically connected to one another for purposes of protecting items, components and people from destructive levels of sound. The geometry of the nozzles and chambers are designed for economical additive manufacture with acoustic infills.

An acoustic-metamaterial acts as a sound reducing filter in that the level of sound that exits the structure is much less than the magnitude of sound that enters the structure. In forming the structure, modular stages of a given geometry are stacked upon one another to create a cell. Each stage of the cell is provided with a nozzle that is acoustically connected to the nozzles of other stages of the cell. The stages have chambers that are positioned radially or laterally outside of the respective nozzles, with the chambers of the cell being acoustically connected to one another. An amalgamation of cells are arranged in an adjacent formation, with chambers of the cells being acoustically connected to one another for purposes of protecting items, components and people from destructive levels of sound.

The type of acoustic absorber comprises a micro-perforated plate, a cavity behind the micro-perforated plate, a slender and curved main acoustic propagation passage communicating with the cavity, and a set of acoustic filters arranged along the main acoustic propagation passage. These acoustic filters have different cut-off frequencies and are arranged in the order of the cutoff frequencies from high to low from the open end to the closed end of the main acoustic propagation passage. The acoustic filter comprises a section of the main acoustic propagation passage and at least one cavity communicating with the main acoustic propagation passage. The type of acoustic absorber is characterized by adopting a main acoustic propagation passage to provide different phase delay for a micro-perforated plate to realize that a micro-perforated plate effectively absorbs broadband acoustic waves, and by combing the close arrangement of main acoustic propagation passage to achieve the ultra-thin structure.

A sound absorbing structure includes a perforated surface with a plurality of through-holes, a first cavity that has a portion extending non-parallel to a normal direction of the perforated surface, the first cavity being breathable between an interior and exterior of the first cavity via the plurality of through-holes existing in a first region of the perforated surface, and a second cavity that is breathable between an interior and exterior of the second cavity via the plurality of through-holes existing in a second region adjacent to the first region of the perforated surface.

A sound absorbing structure includes a perforated surface with a plurality of through-holes, a first cavity that has a portion extending non-parallel to a normal direction of the perforated surface, the first cavity being breathable between an interior and exterior of the first cavity via the plurality of through-holes existing in a first region of the perforated surface, and a second cavity that is breathable between an interior and exterior of the second cavity via the plurality of through-holes existing in a second region adjacent to the first region of the perforated surface.

Broadband acoustic absorbers may be capable providing good absorption performance between 0 and 3,000 Hz, and particularly below 1,000 Hz. Reeds may be incorporated in a single layer, multiple layers, or bundles. Such broadband acoustic absorbers may be applied for acoustic absorption in aircraft, spacecraft, residential and commercial buildings, vehicles, industrial environments, wind tunnels, or any other suitable environment or application where noise reduction is desired.

Systems for magnetoacoustically transferring sound across an acoustic barrier include first and second acoustic resonators positioned on opposite sides of the barrier. Each of the first and second resonators includes an attached magnet. Via magnetic coupling between the magnets, an acoustic oscillation at the first resonator induces an oscillation of the same frequency at the second resonator. Thus sound waves absorbed at the first resonator are magnetically transferred across the barrier to the second resonator, from which they are emitted.

Embodiments provide an apparatus for sound conversion, wherein the apparatus includes a sound channel and a sound transducer coupled to the sound channel, wherein the apparatus comprises an acoustic low-pass filter arranged in the sound channel.

Embodiments provide an apparatus for sound conversion, wherein the apparatus includes a sound channel and a sound transducer coupled to the sound channel, wherein the apparatus comprises an acoustic low-pass filter arranged in the sound channel.

A sound processor comprises one or more electrical signal outputs configured to generate a plurality of electrical signals. The plurality of electrical signals are generated in specific tuned audio frequency bands in respective audio channels, in response to sound information received at the sound processor in the specific tuned audio frequency bands. The sound processor further comprises a transmitter coupled to the one or more electrical signal outputs for transmission of the plurality of electrical signals. The transmitter is configured to transmit the electrical signal in the respective audio channel over a separate respective transcutaneous communication link.