A noise controlling method, comprising: generating one reference signal representing a primary noise; generating one secondary noise in response to a control signal, for cancelling the primary noise; generating one error signal representing a superposition of the primary noise and the secondary noise at a position. The method further comprises: generating at least one additional reference signal, and/or at least one additional secondary noise, and/or at least one additional error signal; and generating the control signal(s) for generating the secondary noise(s), by executing an adaptive subband filtering algorithm based on the reference signal(s) and the error signal(s); wherein the step of generating the control signal(s) comprises: decomposing the reference signal(s) and the error signal(s) into subband reference signal(s) and subband error signal(s), respectively, for each subband of a plurality of subbands; updating a subset of one or more subband adaptive filters for at least one subband of the plurality of subbands, based on a subset of the subband reference signal(s) of the at least one subband and a subset of the subband error signal(s) of the at least one subband, wherein at least one of said three subsets is a proper subset; updating at least one fullband adaptive filter based on the updated subband adaptive filter(s); generating the control signal(s) by filtering the reference signal(s) by the updated at least one fullband adaptive filter.

A active noise cancellation (ANC) system may include an adaptive filter divergence detector for detecting divergence of the one or more controllable filters as they adapt, based on various temporal or frequency domain amplitude characteristics. Upon detection of a controllable filter divergence, the ANC system may be deactivated, or certain speakers may be muted. Alternatively, the ANC system may modify the diverged controllable filters to restore proper operation of the noise cancelling system. This may include adjusting a leakage value of an adaptive filter controller.

A noise suppressor includes a memory; and a processor coupled to the memory, the processor is configured to: acquire a noise signal in a vicinity of a head region of an occupant seated in a vehicle seat; generate a control sound having an opposite phase to the acquired noise signal; acquire a sound signal having a predetermined frequency that is different from the noise signal; and output, as an output sound signal, the acquired sound signal in combination with the generated control sound.

An active noise reduction device includes: an adaptive filter that generates a cancelling signal by applying an adaptive filter to a reference signal that has a correlation with noise in a space in an automobile, the cancelling signal being used to output a cancelling sound for reducing the noise; and a filter coefficient updater that calculates a coefficient of the adaptive filter based on a predetermined update equation. At a first timing at which the output of the cancelling sound is started, the filter coefficient updater uses a first coefficient as an initial value of the update equation, the first coefficient being the coefficient of the adaptive filter calculated by the filter coefficient updater at a second timing that is prior to the first timing.

An active noise control device includes a basic signal generating unit configured to generate a basic signal corresponding to a resonance frequency of a vibration sensor, a first adaptive filter configured to generate a sensor resonance simulation signal simulating a signal acquired while the vibration sensor is resonating by performing a filtering process on the basic signal, a computation unit configured to calculate a second reference signal that is a difference between a first reference signal acquired by the vibration sensor and the sensor resonance simulation signal, and a second adaptive filter configured to generate a control signal by performing a filtering process on the second reference signal.

An active noise control device includes a determination unit configured to determine whether an abnormality has occurred in an acceleration sensor based on a direct-current component of a reference signal acquired by the acceleration sensor attached to a vehicle, and a control unit configured to, when the determination unit determines that an abnormality has occurred in any of a plurality of the acceleration sensors, stop generation of the control signal based on the reference signal acquired by the acceleration sensor that has been determined to have the abnormality, and stop updating a filter coefficient of an adaptive filter configured to perform the filtering process on the reference signal acquired by the acceleration sensor that has been determined to have no abnormality.

An active noise reduction device includes a first adaptive filter, a first filter coefficient updater, and a controller that determines, based on a first parameter of the first adaptive filter, whether first noise control based on a first cancelling sound is in a stable state or an unstable state. The controller transitions the first filter coefficient updater to a restriction state in which an effect of reducing first noise is smaller than in a normal state when it is determined that the first noise control is in the unstable state while the first filter coefficient updater is updating a coefficient of the first adaptive filter in the normal state, and transitions the first filter coefficient updater back to the normal state when it is determined that the first noise control is in the stable state while the first filter coefficient updater is in the restriction state.

A system is provided for actively mitigating noise caused by vibration of a thin vehicle front windshield in an occupant compartment of a vehicle. The system includes a pair of laser scanners configured to be mountable inside the vehicle occupant compartment. Each laser scanner is configurable to scan an associated initial portion of the windshield simultaneously with the other laser scanner, when the windshield is vibrating.

A system includes a microphone unit coupled to a roof of an autonomous vehicle. The microphone unit includes a microphone board having a first opening. The microphone unit also includes a first microphone positioned over the first opening and coupled to the microphone board. The microphone unit further includes an accelerometer. The system also includes a processor coupled to the microphone unit.

A noise reducing system for a tracked vehicle, the tracked vehicle comprising a cab and at least one track that extends along a direction of travel of the vehicle and comprises at least a plurality of bars, such as metal bars, transverse to the direction of travel. The noise reducing system comprising a control unit and an acoustic wave emitter connected to the control unit for being controlled by the control unit, the noise reducing system comprising an acoustic input and being configured to emit an acoustic equalization wave, phase shifted with respect to the noise and determined on the basis of the acoustic input, to reduce the noise, in particular the noise generated by the tracks.