A method for feedforward noise cancellation in an enclosed space within a structure is provided. The method comprises placing a microphone array inside an inner surface of the enclosed space and conducting modal testing on an outside surface of the enclosed space, wherein the modal testing comprises multiple incoherent noise sources corresponding to locations of microphones in the microphone array. Noise generated by the modal testing is processed to create a number of acoustic mathematical models of the enclosed space. In response to incoherent noise within the enclosed space, a noise canceling signal is generated according to an output of the mathematical models.

An active noise cancellation system (1) for cancelling environment noise perceived by a driver or passenger seated in a seat (3) mounted in a cabin of a vehicle, in combination with said seat, the seat comprising a seat cushion (19), a seat back (21) coupled to the seat cushion at a bottom end and extending upwards to a seat shoulder (23), and a headrest (22) coupled to the seat back, extending upwardly from the seat shoulder, the active noise cancellation system comprising an active noise cancellation circuit (ANC) (30), a plurality of microphones (10) mounted in the headrest and connected electrically to the ANC, and a plurality of speakers (16) mounted in the seat and connected electrically to the ANC circuit. The plurality of microphones comprises at least one first microphone mounted on a right side of the headrest and at least one second microphone mounted on a left side of the headrest, and the plurality of speakers comprises at least one first speaker mounted in the seat shoulder on a left side and at least one second speaker mounted in the seat shoulder on a right side, the right speaker configured to generate a noise cancellation sound from a noise signal picked up by the right microphone processed by the ANC circuit and the left speaker configured to generate a noise cancellation sound from a noise signal picked up by the left microphone processed by the ANC circuit.

Vertical take-off and landing (VTOL) aircraft can provide opportunities to incorporate aerial transportation into transportation networks for cities and metropolitan areas. However, VTOL aircraft may be noisy. To accommodate this, the aircraft may utilize onboard sensors, offboard sensing, network, and predictive temporal data for noise signature mitigation. By building a composite understanding of real data offboard the aircraft, the aircraft can make adjustments to the way it is flying and verify this against a predicted noise signature (via computational methods) to reduce environmental impact. This might be realized via a change in translative speed, propeller speed, or choices in propulsor usage (e.g., a quiet propulsor vs. a high thrust, noisier propulsor). These noise mitigation actions may also be decided at the network level rather than the vehicle level to balance concerns across a city and relieve computing constraints on the aircraft.

Arrangements for communication and/or noise attenuation within an aircraft, and aircraft and methods for making aircraft including such arrangements are provided. In one example, an arrangement includes an array of first microphones cooperatively configured to be directed towards a first aircraft operator when disposed in a first cockpit seat to receive a first communication input from the first aircraft operator. An array of first speakers is cooperatively configured to be directed towards the first aircraft operator when disposed in the first cockpit seat to provide a first communication output to the first aircraft operator.

A method of using an acoustic resonator including receiving at a first stage of a resonator an incoming acoustic wave. The method further includes resonating the incoming wave with a flexible membrane, a taper of the flexible membrane, and a cavity of a first stage, thereby producing synergistic effect on a resulting acoustic resonance. Additionally, the method includes transforming an acoustic energy associated with the incoming acoustic wave into an elastic energy, wherein the elastic energy is channeled through the flexible membrane, thereby reducing an intensity of the incoming acoustic wave and resulting in a first reduced incoming acoustic wave. Further the method includes transferring the first reduced incoming acoustic wave through a hole of a neck of the flexible membrane. The method also includes transferring a first pressure wave caused by a perturbation in the flexible membrane into a second stage, thereby producing a second acoustic wave.

A noise cancellation system for cancelling sounds within a vehicle. The noise cancellation system includes microphones, a camera, a controller, and speakers. The microphones are disposed adjacent to occupant locations, and configured to generate microphone signals representative of noise sounds and cancellation audio sounds. The camera is configured to generate a video signal that captures head configurations of the occupants. The controller is configured to receive rotor control signals, calculate hearing locations based on tracking data of the head configurations of the occupants, and generate a speaker signals based on the hearing locations, the microphone signals, and the rotor control signals. The speakers are configured to generate the cancellation audio sounds. The cancellation audio sounds attenuate the noise sounds.

An urban air mobility (UAM) noise reduction system and method are provided, where the UAM noise reduction system includes a UAM configured to detect and to provide rotation per minute (RPM) information of a propeller and location coordinate information, and a noise canceling device configured to predict a noise canceling sound wave amplitude on the basis of the RPM information of the propeller and the location coordinate information received through the UAM and to output a noise canceling sound wave corresponding to the predicted noise canceling sound wave amplitude to the UAM.

A loudspeaker unit for producing sound at bass frequencies an array of two or more diaphragms. The first radiating surface and the second radiating surface are located on opposite faces of the diaphragm, and one or more of the diaphragms are included in a first subset of the diaphragms and one or more of the diaphragms are included in a second subset of the diaphragms; a plurality of drive units.

A drone includes a motor, a noise receiver, a camera, a distance measure, and a directed sound beam generator. The noise receiver is configured to detect a noise caused by the motor. The camera is configured to capture an image of an area when the drone is in the air. The distance measure is configured to measure a distance between the drone and a particular point in the captured image. The directed sound beam generator is configured to emit a sound beam that is directed to a particular direction. The drone further includes a processor configured to analyze the detected noise to determine a frequency spectrum of the detected noise. The processor is further configured to analyze the captured image to identify a target, and cause the directed sound beam generator to emit a sound beam to actively cancel at least a portion of the noise directed to the target.

A noise reduction device includes a processor that converts a noise signal collected by a microphone disposed in a control space into a noise signal in a frequency domain, a storage that stores the converted noise signal in the frequency domain as a reference signal, and a signal generator that generates a noise reduction signal for reducing the noise signal collected by the microphone at a control position of the control space. The processor determines whether or not the noise signal is non-stationary noise based on a frequency characteristic of the converted noise signal in the frequency domain and a frequency characteristic of the reference signal. When it is determined that the noise signal is the non-stationary noise, the processor controls the signal generator so as to cancel generation of the noise reduction signal.