A device for manipulating an incident acoustic wave to generate an acoustic output is described wherein the device comprises a plurality of unit cells arranged into an array, at least some of said unit cells being configured to introduce time delays to an incident acoustic wave at the respective positions of the unit cells within the array of unit cells, such that said plurality of unit cells define an array of time delays to thereby define a spatial delay distribution for manipulating an incident acoustic wave to generate an acoustic output. The array of time delays may be re-configured to vary the spatial delay distribution of the device in order to generate different acoustic outputs. Also described are methods for designing or configuring such devices.

An apparatus is provided. The apparatus includes a plurality of flow guiding structures spatially aligned in a first row, each of the plurality of flow guiding structures comprising a fin-shape to funnel airflow at a trailing edge of each of the plurality of flow guiding structures. The apparatus also includes a plurality of flow separating structures spatially aligned in a second row interleaved between each of the plurality of flow guiding structures, each of the plurality of flow separating structures comprising a fin-shape configured to split airflow received from the plurality of flow guiding structures.

An apparatus is provided. The apparatus includes a plurality of flow guiding structures spatially aligned in a first row, each of the plurality of flow guiding structures comprising a fin-shape to funnel airflow at a trailing edge of each of the plurality of flow guiding structures. The apparatus also includes a plurality of flow separating structures spatially aligned in a second row interleaved between each of the plurality of flow guiding structures, each of the plurality of flow separating structures comprising a fin-shape configured to split airflow received from the plurality of flow guiding structures.

Passively controlled acoustic metamaterials allow transmission of low amplitude acoustic (sound) waves having a resonance frequency and reflect waves having a substantially different frequency. Such materials also reflect waves having the resonance frequency when those waves have an amplitude exceeding a threshold. High amplitude resonance waves cause a resonance membrane contained in unit cells of the metamaterial to contact a rigid structure that is positioned at a longitudinal constraint distance from the resonance membrane in each unit cell. Such contact changes the resonance frequency of the membrane, thereby causing reflection of high amplitude waves. Actively controlled acoustic metamaterials include a ferromagnetic layer on the membrane and an electromagnetic positioned in each unit cell. Activation of the electromagnetic displaces the membrane and thereby shifts the resonance frequency of the membrane, on demand.

Passively controlled acoustic metamaterials allow transmission of low amplitude acoustic (sound) waves having a resonance frequency and reflect waves having a substantially different frequency. Such materials also reflect waves having the resonance frequency when those waves have an amplitude exceeding a threshold. High amplitude resonance waves cause a resonance membrane contained in unit cells of the metamaterial to contact a rigid structure that is positioned at a longitudinal constraint distance from the resonance membrane in each unit cell. Such contact changes the resonance frequency of the membrane, thereby causing reflection of high amplitude waves. Actively controlled acoustic metamaterials include a ferromagnetic layer on the membrane and an electromagnetic positioned in each unit cell. Activation of the electromagnetic displaces the membrane and thereby shifts the resonance frequency of the membrane, on demand.

A sound generating device includes a case and a diaphragm fixed to the inner surfaces of first to fourth side wall portions of the case via a support member. An air chamber surrounded by a top plate, the diaphragm, and portions of the first to fourth side wall portions is formed. A sound emitting chamber that extends between the air chamber and the atmosphere outside of the case terminates at a sound emitting hole which extends across a plurality of surfaces of the case 2.

A sound generating device includes a case and a diaphragm fixed to the inner surfaces of first to fourth side wall portions of the case via a support member. An air chamber surrounded by a top plate, the diaphragm, and portions of the first to fourth side wall portions is formed. A sound emitting chamber that extends between the air chamber and the atmosphere outside of the case terminates at a sound emitting hole which extends across a plurality of surfaces of the case 2.

A road vehicle comprising: a passenger compartment; an internal combustion engine; an exhaust system, which releases into the atmosphere the gases generated by the combustion, is connected to the internal combustion engine, and ends with at least one silencer having at least one outlet pipe; and an exhaust noise transmission device, which is provided with a transmission conduit, which originates close to the outlet pipe of the silencer, ends in the area of a wall of the passenger compartment, and is provided, on the inside, with at least one insulating element, which is arranged inside the transmission conduit so as to tightly seal the transmission conduit.

A road vehicle comprising: a passenger compartment; an internal combustion engine; an exhaust system, which releases into the atmosphere the gases generated by the combustion, is connected to the internal combustion engine, and ends with at least one silencer having at least one outlet pipe; and an exhaust noise transmission device, which is provided with a transmission conduit, which originates close to the outlet pipe of the silencer, ends in the area of a wall of the passenger compartment, and is provided, on the inside, with at least one insulating element, which is arranged inside the transmission conduit so as to tightly seal the transmission conduit.

A breakaway stethoscope includes a chest piece, a headset, a tube, and a coupler. The chest piece captures sounds generated inside a person's body when the chest piece is positioned adjacent the person's body. The headset directs the sounds captured by the chest piece toward a person's ear when the headset is positioned on an ear of the person. The tube connects the chest piece to the headset and conveys the sounds captured by the chest piece toward the headset. The tube has a length and includes a first portion connected to the chest piece and a second portion connected to the headset. The coupler releasably connects the tube's first portion to the tube's second portion and releases one of the tube's portions when the tube experiences a force that urges at least one of the tube's portions to move away from the coupler.