Abstract: Embodiments described herein relate to a device for detecting the position of electromagnetic noise. The device includes a detector that includes coils that produce voltages in the presence of electromagnetic noise of a defined frequency. The device further includes a controller that senses the voltages and determines a position of the electromagnetic noise relative to the device according to the voltages.

Abstract: 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.

Abstract: A broadband sparse acoustic reflector includes a periodic array of laterally spaced apart unit cells, each unit cell having a plurality of longitudinally positioned Helmholtz resonators. Each unit cell includes a Helmholtz resonator having a neck that places the resonator interior in fluid communication with an ambient fluid, in the lateral direction. Each Helmholtz resonator of the unit cell has a different resonance frequency, providing broadband reflection.

Abstract: A sound suppression assembly is provided for absorbing acoustic energy from an air circulation device. The assembly includes an air circulation device, such as an axial fan, and a plurality of sparsely-arranged two-sided Helmholtz unit cells disposed in a periodic array. Each unit cell includes a lossy resonator and a lossless resonator. The lossy resonator includes a first chamber portion bounded by at least one first boundary wall defining a first chamber volume, and a first neck forming an opening in the first chamber portion. The lossless resonator includes a second chamber portion bounded by at least one second boundary wall defining a second chamber volume, and a second neck forming an opening in the second chamber portion. The unit cells can be positioned in a circular pattern with the first neck of the lossy resonators directed to a source of acoustic energy from the air circulation device.

Abstract: Devices for superscattering a plate bending wave include a solid plate, and a circular array of spring-mass resonators positioned on a surface of the plate. All resonators in the circular array have a resonance frequency that can be matched to a frequency of a target flexural wave. The circular array has a diameter that can further be matched to the wavelength of the target flexural wave. Scattering efficiencies can exceed several multiples of the theoretical limit.

Abstract: Embodiments described herein relate to a device for detecting the position of electromagnetic noise. The device includes a detector that includes coils that produce voltages in the presence of electromagnetic noise of a defined frequency. The device further includes a controller that senses the voltages and determines a position of the electromagnetic noise relative to the device according to the voltages.

Abstract: In one embodiment, a flexural wave absorption system includes a base member connected to a beam that may be subject to flexural waves, an arm member, connected to the base, disposed substantially in parallel alignment with the beam, a mass member connected to a distal end of the arm member, a piezoelectric patch, connected to the arm member, that generates electricity in response to a flexural wave propagating through the beam, and a shunting circuit, connected to the piezoelectric patch, that dissipates electricity generated by the piezoelectric patch to absorb the flexural wave.

Abstract: A system can improve the performance of an electroacoustic absorber. The system includes a loudspeaker and an absorber operatively positioned relative to the loudspeaker. The absorber can be configured to absorb sound waves. A control circuit can be operatively connected to the loudspeaker. The control circuit can be configured to tune the resonance of the loudspeaker and therefore cause one or more acoustic characteristics, such as acoustic impedance, of the loudspeaker to be adjusted.

Abstract: A system is provided for actively mitigating noise caused by vibration of a thin vehicle front windshield in an occupant compartment of a vehicle. The system includes a pair of laser scanners configured to be mountable inside the vehicle occupant compartment. Each laser scanner is configurable to scan an associated initial portion of the windshield simultaneously with the other laser scanner, when the windshield is vibrating.

Abstract: A device can be configured to cause the superscattering of acoustic waves and/or to enable incident angle-dependent scattering. The acoustic superscattering device can include a body that has an outer peripheral surface. One or more resonators can be defined in the body. The one or more resonators can open to the outer peripheral surface of the body. When there are a plurality of resonators, the resonators are not in communication with each other within the body. The acoustic superscattering device can be configured to cause the superscattering of a target acoustic wave impinging upon the body.

Abstract: In one embodiment, a flexural wave absorption system detects, with a sensor attached to a beam, an incident wave propagating in the beam. The system determines, based on a signal from the sensor generated in response to the incident wave, an amplitude and phase of the incident wave propagating in the beam and controls an actuator connected to the beam to generate a suppression wave, based on the amplitude and the phase of the incident wave, that reduces a coefficient of reflection of the incident wave across a broadband frequency range.

Abstract: A tunable metamaterial structure can have a flexible substrate that is elastically deformable. The tunable metamaterial structure can have a photo-responsive stiffness-modulating patch. The photo-responsive stiffness-modulating patch can be fixed to a surface of the flexible substrate. The photo-responsive stiffness-modulating patch can include a piezoelectric element and a photo-responsive element. The piezoelectric element and the photo-responsive element are electrically connected to one another.

Abstract: Frequency adjustable quarter-wavelength resonators have a movable end wall defined by a surface of a sphere that is moved within the resonator tube. The sphere can be ferromagnetic, enabling it to be moved by magnetic interactions with moving external magnetic elements, or by a variable external magnetic field, controlled by power modulation to external electromagnets. The resonators can optionally be helical or otherwise curved, and the spherical shape of the structure forming the end wall enables it to navigate curves in the resonator tube.

Abstract: A system for determining at least one characteristic of a transmitting coil generating a magnetic field may include a first measurement coil being wound in a first direction, a second measurement coil being wound in a second direction, a voltage measuring device, and at least one processor in communication with the voltage measuring device. The first measurement coil and the second measurement coil may be adjacent to one another. The voltage measuring device may be configured to measure a first voltage of the first measurement coil and a second voltage of the second measurement coil in response to the magnetic field generated by the transmitting coil. The at least one processor may be configured to determine the at least one characteristic of the transmitting coil based on a ratio between the first voltage and the second voltage at a predetermined frequency.

Abstract: Devices for detecting plate bending, or flexural, waves include at least two mechanical resonators positioned on a plate in a specified configuration. Each mechanical resonator has an associated oscillation amplitude detector, such as a laser vibrometer, configured to detect resonant oscillation of the mechanical resonator in response to an incident flexural wave. A ratio of frequency-dependent oscillation data for each mechanical oscillator is compared to a calibration curve to determine the angle of incidence of the flexural wave.

Abstract: A system and related method can self-adaptively absorb a flexural wave acting on a beam. The method includes the steps of receiving an input signal representing a frequency response of a flexural wave acting on the beam, determining a spring constant for absorbing the flexural wave based on the input signal, a damping value of a damper acting on the beam, and a mass value of a mass acting on the beam, and applying a spring constant voltage based on the spring constant to a piezoelectric device connected to the beam. The piezoelectric device has a variable spring value that varies based on the voltage applied to the piezoelectric device. The piezoelectric device's variable spring value is approximately equal to the spring constant value when the spring constant voltage is applied to the piezoelectric device.

Abstract: One-way sound transmission devices include a planar, acoustically reflective substrate having an aperture that is traversed by an elastic membrane. On one face of the substrate, two resonators are symmetrically spaced apart from the membrane at a first distance, configured to enable constructive interference between the resonators and the membrane. On the opposite face of the substrate, two other resonators are symmetrically spaced apart from the membrane at a second, greater, distance, configured to enable destructive interference between the resonators and the membrane.

Abstract: A broadband sparse acoustic absorber includes a periodic array of spaced apart unit cells, generally having a lateral fill factor less than 0.5. Each unit cell includes a pair of joined, and inverted, Helmholtz resonators, having longitudinal and lateral neck portions that are perpendicular to one another. The longitudinal neck portions are typically covered and/or filled with acoustic absorbing material. Sound suppression systems include sound emitting devices that are at least partially surround by one or more such arrays.

Abstract: A system is provided for actively mitigating noise caused by vibration of a thin vehicle front windshield in an occupant compartment of a vehicle. The system includes a pair of laser scanners configured to be mountable inside the vehicle occupant compartment. Each laser scanner is configurable to scan an associated initial portion of the windshield simultaneously with the other laser scanner, when the windshield is vibrating.

Abstract: Devices for superscattering a plate bending wave include a solid plate, and a circular array of spring-mass resonators positioned on a surface of the plate. All resonators in the circular array have a resonance frequency that can be matched to a frequency of a target flexural wave. The circular array has a diameter that can further be matched to the wavelength of the target flexural wave. Scattering efficiencies can exceed several multiples of the theoretical limit.