An unmanned flying object, capable of suppressing an increase in overall size while having a configuration to reduce noise, is provided. The unmanned flying object includes a duct that corresponds to: at least one generator that generates airflow; at least one microphone; and at least one speaker. The duct covers the at least one generator in a direction perpendicular to an airflow direction, passes the airflow in the airflow direction, includes a space between inner and outer peripheral surfaces, and defines an opening at the end of the space in the airflow direction. A shape of the inner peripheral surface is tapered in the airflow direction. The at least one microphone is positioned in the space. The at least one speaker is positioned closer to the at least one generator than the at least one microphone.

The improved active noise cancellation system for forced air heating or cooling systems onboard aircraft employs a duct having a proximal end coupled to the fan unit to entrain the airflow stream in the direction of a distal end of the duct. A reference sensor is positioned within the proximal end of the duct. A means is provided for injecting an audio frequency control signal into the airflow stream in a manner that does not substantially impede the airflow stream. An error sensor is positioned at the distal end of the duct where it is responsive to sounds carried by the airflow stream, including the audio frequency control signal. An electronic circuit coupled to the reference sensor and to the error sensor supplies a noise abating control signal to energize the control transducer and thereby substantially reduce at least one noise harmonic of the fan unit through destructive interference.

According to one embodiment, a sound emitting apparatus includes an elastic member, three or more excitation actuators, and a control circuit. The elastic member has an annular shape. The excitation actuators are arranged at a predetermined angular interval on the elastic member and are configured to apply vibration to the elastic member. The control circuit is configured to generate drive signals for driving the three or more excitation actuators. There is a phase difference between drive signals for two excitation actuators separated by the predetermined angular interval, the phase difference depending on an order of a Lobe mode being a vibration mode excited on the elastic member and the predetermined angular interval.

An apparatus on a vehicle comprises one or more sensors, one or more nozzles that output fluid to clean the respective one or more sensors, and a compressor that generates fluid such as compressed air. The compressor is in fluid communication with the one or more nozzles. The apparatus further comprises one or more processors, and a memory storing instructions that, when executed by the one or more processors, cause the system to determine information of an acoustic emission from the compressor and to counteract the acoustic emission based on the determined information.

A fan noise cancellation device comprises a base with a resonant ring formed with a plurality of resonance channels and a cover coupled to the base. Each resonance channel comprises an inner channel and an outer channel. Each inner channel has an opening to the resonant ring and has a length corresponding to a frequency. A baffle positioned in each inner channel determines an effective length of the inner channel. The inner channel baffles are coupled to the cover, wherein rotation of the cover relative to the resonance ring changes the position of the inner channel baffles to change the effective lengths of the inner channels to adjust the fan noise cancellation waveform frequency. Vanes on the cover are positioned in an airflow such that the airflow rotates the cover, and a spring in each resonance channel counteracts the rotation to adjust the inner channels.

An unmanned aerial vehicle capable of employing active noise cancelling without being influenced by wind from a rotor is provided. The unmanned aerial vehicle includes a processor and at least one speaker. The processor acquires operational information regarding each of at least one generator and generates an opposite phase signal having an opposite phase relative to a signal corresponding to the operational information. The at least one generator generates a force to fly the unmanned aerial vehicle. The operational information correlates with noise generated by each of the at least one generator. The at least one speaker outputs sound based on the opposite phase signal.

A body dryer includes an airflow generator to generate a flow of air, an inlet to pass air from the surroundings to the airflow generator, an outlet to vent the air from the airflow generator, a body, and a movable bar, the bar supported by the body. A drive assembly is provided between the body and the bar, the bar movably driven relative to the body. A noise cancellation device is provided to cancel or reduce noise in at least one of the airflow generator and the drive assembly.

Aspects of the invention are directed towards a system and method for noise suppression. One or more embodiments of the invention describe the method comprising steps of receiving noise by a microphone and deriving a noise signal from the noise, the noise produced by a fan of a fire/smoke detection unit while drawing air and detecting the speed of the fan of the fire/smoke detection unit. The method further describes steps of amplifying the noise signal by the amplifier received from the microphone and producing an anti-phase noise signal by shifting a phase of the amplified noise signal received from the amplifier wherein the anti-phase noise signal is dependent on the detected speed of the fan. The method further describes steps of outputting the anti-phase noise signal through a speaker to suppress the noise produced by the fan of the fire/smoke detection unit while drawing the air.

A method for active noise reduction in an electric or hybrid vehicle includes (i) detecting noise in an area surrounding the vehicle by at least one sound recording apparatus which is attached to the vehicle, and (ii) generating anti-phase sound by at least one sound output apparatus, which is attached to the vehicle, depending on a signal recorded by the sound recording apparatus. The generated anti-phase sound is generated with respect to a portion of the noise in the area surrounding the vehicle and is output into the area surrounding the vehicle. Also described is a corresponding electric or hybrid vehicle which is designed to perform active noise reduction with respect to its ambient noise.

A method for active noise reduction in an electric or hybrid vehicle includes (i) detecting noise in an area surrounding the vehicle by at least one sound recording apparatus which is attached to the vehicle, and (ii) generating anti-phase sound by at least one sound output apparatus, which is attached to the vehicle, depending on a signal recorded by the sound recording apparatus. The generated anti-phase sound is generated with respect to a portion of the noise in the area surrounding the vehicle and is output into the area surrounding the vehicle. Also described is a corresponding electric or hybrid vehicle which is designed to perform active noise reduction with respect to its ambient noise.