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.

A rotor blade with a leading edge and a trailing edge is provided, wherein the rotor blade is for being exposed to a fluid flowing substantially from the leading edge to the trailing edge, the rotor blade includes at least three sensors designed for detecting flow characteristics of the fluid and providing respective sensor signals, wherein the sensors are arranged with a non-uniform spacing, and the rotor blade further includes at least one actuator for producing an anti-noise signal based on a sensor signal, the sensors and the actuator are arranged at the surface of the rotor blade, and the actuator is arranged and prepared such that flow-induced edge noise of the rotor blade, which is generated by the fluid, is at least partly cancelled out by the anti-noise signal. A method for creating such rotor blade and a related wind turbine is also provided.

The present disclosure presents a feedback active noise control system and strategy with online secondary-path modeling, and belongs to the technical field of active noise control. The linear prediction subsystem takes the residual noise as its input and separates the remaining sinusoidal noise from the broadband noise. The remaining sinusoidal noise is used effectively not only to update the controller but also to scale the auxiliary noise, while the broadband noise serves as a desired input of online secondary-path modeling subsystem. In this way, the coupling between the controller and the online secondary-path modeling subsystem is significantly mitigated, leading to both faster convergence and improved noise reduction performance. A practical scheme for refreshing the entire system is also developed to enhance its robustness against even abrupt changes with the secondary path or the primary noise. The present disclosure enhances the applicability of feedback active noise control in practical applications.

According to an embodiment, a sound emitting apparatus includes a helical hollow tube and at least three sound wave sources. The helical hollow tube helically extends in a circumferential direction to form an annular shape as a whole. The first helical hollow tube includes a plurality of openings. The at least three sound wave sources are coupled to the first helical hollow tube and are configured to supply a sound wave to the first helical hollow tube.

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.

A work machine includes microphones inside the housing. The microphones are configured to collect sound inside the housing, and output sound signals that are electrical signals corresponding to the collected sound. The sound includes an operating noise generated inside the housing due to motion of a machine. The microphones are arranged at different locations inside the housing. The work machine is configured to execute a process related to the operating noise based on the sound signals from the microphones.

The work machine includes a path leading into a housing from an opening. The path is provided to control an airflow generated by motion of a machine. The work machine includes a microphone. The microphone is configured to collect sound in the housing, including operating noise generated in the housing by the motion of the machine. The work machine further includes a structure that defines a receiving space for the microphone along the path through which the operating noise propagates outside the housing. The structure includes an open structure that connects the receiving space with the path and faces downstream in the path. The structure surrounds the receiving space upstream of the open structure in the path.

There are provided a control signal generation unit 120 that generates a control signal on the basis of a cosine wave signal and a sine wave signal whose frequencies are a control frequency identified according to a vibration noise source, and a correction value update unit that updates a correction value to a value for decreasing signal power of an error signal on the basis of a relationship between increase and decrease of the signal power of the error signal obtained from remaining vibration noise that remains after interference sound that is generated on the basis of the control signal and propagates through a secondary route interferes with vibration noise generated from the vibration noise source and increase and decrease of the correction value used for correction of the control frequency.

The present disclosure presents a feedback active noise control system and strategy with online secondary-path modeling, and belongs to the technical field of active noise control. The linear prediction subsystem takes the residual noise as its input and separates the remaining sinusoidal noise from the broadband noise. The remaining sinusoidal noise is used effectively not only to update the controller but also to scale the auxiliary noise, while the broadband noise serves as a desired input of online secondary-path modeling subsystem. In this way, the coupling between the controller and the online secondary-path modeling subsystem is significantly mitigated, leading to both faster convergence and improved noise reduction performance. A practical scheme for refreshing the entire system is also developed to enhance its robustness against even abrupt changes with the secondary path or the primary noise. The present disclosure enhances the applicability of feedback active noise control in practical applications.

A food waste disposer system (300) has active noise control of food waste disposer noise that is generated by the food waste disposer (302) when a motor of the food waste disposer (302) is running. The food waste disposer (302) has a food conveying section that conveys food waste to a grinding section. The grinding section has a rotatable shredder plate that is rotated by a motor of a motor section. Active noise sound waves (310) are radiated into an area (313) where the food waste disposer noise is to be controlled at an amplitude and frequency to at least cancel or mask the food waste disposer noise.