A method of designing an acoustic waveguide in which acoustic waves travelling along the waveguide are treated as exhibiting single parameter behaviour, and in which the waveguide provides a boundary confining the acoustic waves as they travel along the wave propagation path and has two substantially parallel, primary surfaces spaced apart a distance less than a wavelength of a high frequency acoustic wave. The primary surfaces may be planar, curved, or a combination of planar portions and curved portions.

There is provided a system for estimating a total acoustic attenuation of a hearing protection device including an interface at a distal end and a sound canal extending from the interface to a sound opening at a medial end of the hearing protection device. The system comprises: a measurement unit including a loudspeaker and a microphone and being attachable to the interface in such a manner that, when the hearing protection device is worn in an ear canal of a user, the loudspeaker and the microphone are in acoustic communication, via the sound canal of the hearing protection device; a control unit configured to provide the loudspeaker with test audio signals to generate test sounds in the occluded ear canal volume and to receive test response audio signals captured by the microphone from the test sounds; and an evaluation unit configured to estimate a leakage acoustic impedance.

An apparatus worn on a head of the user. The apparatus includes a hat having a front, an opposite back, and a crown position at the front. A sound directing assembly has a body coupled to the crown of the hat. The body of the sound directing assembly is configured to receive sound. A sound tube extends from the body to an earpiece that is configured to be inserted into an ear of the user. The sound tube is configured to direct the sound received by the body to the earpiece such that the user can hear the sound.

An apparatus worn on a head of the user. The apparatus includes a hat having a front, an opposite back, and a crown position at the front. A sound directing assembly has a body coupled to the crown of the hat. The body of the sound directing assembly is configured to receive sound. A sound tube extends from the body to an earpiece that is configured to be inserted into an ear of the user. The sound tube is configured to direct the sound received by the body to the earpiece such that the user can hear the sound.

An acoustic waveguide having high-Q resonator characteristics is disclosed and a fabrication method is described. Various waveguide-based test-vehicles, implemented in single crystal silicon and transduced by thin aluminum nitride films, are demonstrated. Silicon resonators with type-I and type-II dispersion characteristics are presented to experimentally justify the analytical mode synthesis technique for realization of high quality-factor silicon Lamb wave resonators. An analytical design procedure is also presented for geometrical engineering of the waveguides to realize high-Q resonators without the need for geometrical suspension through narrow tethers or rigid anchors. The effectiveness of the dispersion engineering methodology is verified through development of experimental test-vehicles in 20 μm-thick single-crystal silicon (SCS) waveguides with 500 nm aluminum nitride transducers.

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.

An acoustic lens is presented that redirects high frequency voice sounds over a barrier to improve the intelligibility of speech when a protective barrier is used to isolate people from each other. The acoustic lens includes curved sheets to delay sound to create focal points on each side of a barrier, where the focal points are lower than the top of the barrier.

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.