Active noise cancellation is employed to address unwanted acoustical noise generated by various equipment associated with an ophthalmic surgical system. Active noise cancellation may be used within a chassis of the ophthalmic surgical system, within an air compressor used with the ophthalmic surgical system, and within a reciprocating surgical probe used with the ophthalmic surgical system.

A silencer is to be used in combination with a range hood system to suppress noise made by a fan. In a silencing circuit, a disturbance detector detects mixing of disturbance sound to a correction signal and an error signal. When the disturbance detector detects the mixing of the disturbance sound, an updating stopper causes a coefficient updater to stop a processing of updating a filter coefficient of a silencer filter, relating to, as an object, at least a frequency band other than a frequency band of the noise.

A method for actively monitoring sound emissions of turbomachinery, in particular turbomachinery which has an electric motor, preferably a ventilator or a turbomachine. A sound signal, which is produced by superimposing the sound emission of the turbomachinery with at least one counter sound signal, is captured by at least one receiver at at least one receiver position and is transmitted to a control unit, wherein the control unit has an artificial intelligence, and a control signal is generated by the artificial intelligence for at least one actuator while taking into consideration the sound signal such that the actuator generates a counter sound signal that interacts with the sound emission of the turbomachinery such that a sound load at least in the region of the receiver position or the receiver positions is reduced.

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.

An acoustic noise attenuator is disclosed comprising a movable body, an energy storage element and an electrical energy dissipater. The movable body is configured to oscillate when a mechanical disturbance caused by a sound wave, such as acoustic noise, is incident thereon. The oscillation of the movable body induces an alternating electrical energy in the energy storage element. The electrical energy dissipater dissipates the induced electrical energy in the form of heat. An acoustic noise attenuator assembly and a metamaterial structure comprising such acoustic noise attenuators are also disclosed.

A separate active noise cancellation device is installed on an electronic device which includes a circuit board and a noise generating source. The separate active noise cancellation device includes an active noise cancellation controller, a microphone and a speaker, the active noise cancellation controller is installed on and electrically connected to the circuit board, the microphone and the active noise cancellation controller are separately installed, the microphone has a cable provided for electrically connecting the active noise cancellation controller, the microphone is arranged around the noise generating source, the speaker is electrically connected to the active noise cancellation controller and capable of issuing a noise cancelling sound to offset the noise generated by the noise generating source. In this way, the amount of noise may be accurately captured and reduced to overcome the annoying noise problem.

A projector includes an exterior enclosure having an intake port and a discharge port, a heat source, a fan that causes a cooling gas to flow to the heat source, a loudspeaker that is disposed between one of the two openings, and the fan in the channel of the cooling gas and outputs a sound wave according to a drive signal inputted to the loudspeaker, a characteristic data storage section that stores frequency characteristic data on the frequency characteristics of discrete frequency noise, broadband noise, and in-apparatus environmental noise, and a control section that generates the drive signal, and the control section includes a characteristic acquisition section that acquires the frequency characteristic data corresponding to the rotational speed of the fan per unit time, a waveform generation section that generates the waveform of an interference sound, and a signal output section that outputs the drive signal.

Apparatuses and methods for improved noise reduction and voice capture in respiratory protective devices are provided. For example, an example respiratory protective device includes at least one fan component secured to the respiratory protective device, at least one sound sensor component positioned within the respiratory protective device and generating a detected sound signal, and a controller component electronically coupled to the at least one fan component. In some examples, the controller component is configured to receive a detected fan speed signal, retrieve a corresponding noise profile data object, generate a noise-reduced sound signal, and transmit the noise-reduced sound signal to a data communication component.

A cooker hood with function of active noise cancellation is disclosed. The cooker hood comprises a hood body, a chimney, a fan motor, a sound-absorbing member, and an ANC system, in which the sound-absorbing member blocks or destroys a sound wave of a noise sound produced in case of the operation of the fan motor. The ANC system comprises reference microphones, error microphones, an electronic device, and loudspeakers, and is utilized for collecting a noise sound in chimney, generating an anti-noise signal according to the noise sound, and driving the loudspeaker to broadcast an anti-noise sound toward an internal of the chimney. Briefly speaking, the sound-absorbing member and the ANC system are used to apply a passive noise cancellation treatment and an active noise cancellation treatment to the noise sound produced during the operation of the fan motor.

An exemplary noise reducing device for reducing the noise of sound waves propagating through a fluid includes a housing; a primary flow path within the housing configured to receive a first portion of the fluid; and at least one phase shifting flow path within the housing configured to receive a second portion of the fluid, wherein the first portion of the fluid flowing through the primary flow path produces a first sound wave, and wherein the second portion of the fluid flowing through the phase shifting flow path produces a second sound wave out of phase relative to the first sound wave at a target frequency, such that the first sound wave destructively interferes with the second sound wave to reduce noise of the first and second sound waves.