An active noise control unit generates a noise canceling sound of a single frequency that cancels engine sound heard by an occupant and outputs the noise canceling sound to a speaker through an amplifier. A second harmonic detector and a third harmonic detector detect a magnitude of a harmonic component of the noise canceling sound included in sound collected by a microphone. A controller controls a frequency of the noise canceling sound generated by the active noise control unit to a fundamental frequency of the engine sound based on a rotation frequency of the engine, and in addition, causes an output level control unit to control a level of the noise canceling sound to be output to the amplifier so that the level of the noise canceling sound becomes higher when the magnitude of the harmonic component exceeds a predetermined threshold value.

The present disclosure provides an active noise reduction method, a system, and a new energy vehicle. The active noise reduction method includes: obtaining a frequency of a high-frequency noise signal in an acoustic environment, constructing and generating a harmonic masking signal according to the frequency of the high-frequency noise signal, where the harmonic masking signal includes a harmonic signal and a masking signal, and the harmonic signal is a subharmonic wave of the high-frequency noise signal, and inputting the harmonic masking signal into a sound playback apparatus for playback to output a noise reduction construction sound, and performing noise reduction on the acoustic environment.

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.

Disclosed herein are methods for operating an apparatus for generating acoustic compensation signals used to compensate acoustic signals from operation of a motor-vehicle engine, comprising the steps: providing an EOC device, which is designed to generate acoustic compensation signals used to compensate acoustic signals that result from the operation of the engine; providing a device configured using the EOC device as a model; determining at least one audio signal to be output into a passenger compartment of a motor vehicle by means of an audio output device, before said audio signal is captured by an audio capturing element associated with the EOC device; applying an evaluation specification to evaluate the at least one audio signal with respect to at least one evaluation criterion; generating evaluation information with respect to the at least one evaluation criterion; controlling the operation of the EOC device on the basis of the evaluation Information.

An active noise control unit generates a noise canceling sound of a single frequency that cancels engine sound heard by an occupant and outputs the noise canceling sound to a speaker through an amplifier. A second harmonic detector and a third harmonic detector detect a magnitude of a harmonic component of the noise canceling sound included in sound collected by a microphone. A controller controls a frequency of the noise canceling sound generated by the active noise control unit to a fundamental frequency of the engine sound based on a rotation frequency of the engine, and in addition, causes an output level control unit to control a level of the noise canceling sound to be output to the amplifier so that the level of the noise canceling sound becomes higher when the magnitude of the harmonic component exceeds a predetermined threshold value.

A technique of controlling tonal noises produced by an unmanned aerial vehicle (UAV) includes generating thrust with a plurality of rotor units mounted to the UAV to propel the UAV into flight. Each of the rotor units includes a bladed rotor. A rotation rate or a phase delay of at least one of the rotor units is adjusted relative to another of the rotor units. The adjustment causes a spread in the tonal noises generated by the rotor units.

According to one embodiment, a noise reduction device includes speakers, microphones, and a processing circuit. The speakers are arranged around a rotor and emit control sound based on control signals. The microphones are arranged around the rotor and convert the control sound and noise emitted by the rotor into microphone signals. The processing circuit generates the control signals for reducing acoustic power in positions of the microphones, based on the microphone signals, rotation speed of the rotor, and a phase of noise that reaches the microphones from the rotor.

An active device for attenuating the acoustic emissions of an aircraft turbojet engine includes circulation conduits for a pressurized air flow rate supplying rotary elements each having a pulsation system for the delivered air. The rotary elements are controlled in amplitude and phase and deliver, to outlet diffusers, a pulsed air flow rate with a pulsation at the frequency of the noise to be attenuated having an amplitude and a phase adjusted according to a local feedback law with microphones to attenuate the radiated acoustic power.

A method for noise attenuation includes comparing a frequency of noise generated by a plurality of noise sources with a plurality of frequencies associated with a pre-determined noise spectrum and stored in a computer system, identifying one or more noise sources that generate the noise based on the comparison of the frequency of the noise and the plurality of frequencies stored in the computer system; generating anti-noise corresponding to the noise; and outputting the anti-noise using one or more noise mitigation devices associated with the one or more noise sources.

In at least one embodiment, a computer-program product embodied in a non-transitory computer readable medium that is programmed to perform selective active noise cancellation (ANC) for a vehicle is provided. The computer-program product comprising instructions to determine an amount of noise present in a first zone and a second zone and to selectively drive only at least one first loudspeaker in the first zone to generate a first cancellation field to cancel road noise and/or engine noise if the amount of noise in the first zone is greater than the amount of noise in the second zone. The computer-program product comprising instructions to selectively drive only at least one second loudspeaker in the second zone to generate the second cancellation field to cancel road noise and/or engine noise if the amount of noise in the second zone is greater than the amount of noise in the first zone.