Rotor noise cancellation through the use of mechanical means for a personal aerial drone vehicle. Active noise cancellation is achieved by creating an antiphase amplitude wave by modulation of the propeller blades, by utilizing embedded magnets through an electromagnetic coil encircling the propeller blades. A noise level sensor signals the rotor control system to adjust the frequency of the electromagnetic field surrounding the rotor and control the speed of the rotor. An additional method comprises of incorporating a phase lock loop within the control system configured to determine the frequencies corresponding to the rotors and generate corrective audio signals to achieve active noise cancellation.

A work machine includes a housing. The housing at least partly houses a machine. The housing has an opening. The work machine includes a path leading into the housing from the opening. The work machine includes a controller and a speaker. The controller is configured to cause a speaker to output a control sound for reducing operating noise. The operating noise is generated in the housing by motion of the machine and propagates in the path from a source of the operating noise to the opening. The speaker is arranged so that the control sound propagates in the path with its wavefront parallel to a wavefront of the operating noise that propagates in the path.

Example methods, systems, and articles of manufacture may relate to an aerial vehicle. The methods, systems, and articles of manufacture may include receiving an audio signal with a microphone of the aerial vehicle. The methods, systems, and articles of manufacture may also include processing the audio signal to determine at least one of a distance and type of aircraft located near the aerial vehicle. Additionally, the methods, systems, and articles of manufacture may include, based on the determination, performing at least one maneuver of the aerial vehicle.

This disclosure relates to improved techniques for electronic noise cancellation in aircraft and other enclosures. In certain embodiments, an electronic noise cancellation device can be installed in an aircraft. In certain embodiments, the electronic noise cancellation device can include a housing that integrates: one or more audio input devices that are configured to receive an input audio signal; one or more audio output devices configured to output a noise cancellation signal; one or more lighting components; and at least one connector that enables the electronic noise cancellation device to be coupled to an overhead service component of the aircraft. In certain embodiments, the electronic noise cancellation device is adapted to be received in a lighting socket of the overhead service component included within an aircraft enclosure. Other embodiments are disclosed.

Rotor noise cancellation through the use of mechanical means for a personal aerial drone vehicle. Active noise cancellation is achieved by creating an antiphase amplitude wave by modulation of the propeller blades, by utilizing embedded magnets through an electromagnetic coil encircling the propeller blades. A noise level sensor signals the rotor control system to adjust the frequency of the electromagnetic field surrounding the rotor and control the speed of the rotor. An additional method comprises of incorporating a phase lock loop within the control system configured to determine the frequencies corresponding to the rotors and generate corrective audio signals to achieve active noise cancellation.

The voice control device includes a sound source signal input unit, a frequency determination unit, a band controller, a sound image controller, and a voice output unit. The sound source signal input unit inputs a sound source signal of content from a sound source. The frequency determination unit determines a cutoff frequency. The band controller acquires a high frequency signal in a frequency band equal to or higher than the cutoff frequency and a low frequency signal in a frequency band equal to or lower than the cutoff frequency, from the sound source signal of the content. The sound image controller generates a plurality of sound image control signals for controlling sound images of the plurality of speakers, by controlling at least one of a phase and a sound pressure level of the high frequency signal. The voice output unit outputs the low frequency signal to a first speaker, and outputs the plurality of sound image control signals to a second speaker composed of a plurality of speakers.

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.

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.

According to one embodiment, a system for reducing interference noise of rotor and stator blades includes rotor blades, stator blades, loudspeakers, one or more reference microphones, and a controller. The rotor blades rotate about a central axis. The loudspeakers are discretely arranged on a circle that has a center positioned on the central axis. Each loudspeaker generates a control sound. The controller causes the loudspeakers to generate control sounds of a same phase and a same amplitude. The control sounds correspond to the loudspeakers. The r is selected based on a preset attenuation level concerning the interference noise, and the k, where a is a length of the rotor blades, b is a radius of the circle, r=a/b, k is an upper limit wavenumber.

A global active noise control method for a rotorcraft, including: acquiring the acoustic pressure signal at a measuring point of the rotorcraft; predicting the holographic and global sound field of noise of the rotor; reconstructing the reverse sound field of the noise of the rotor; and performing adaptive sound field adjustment based on the optimal phase search.