A noise reduction system includes sensors configured to generate an input signal, an adaptive filter configured to represent a transfer function of a path traversed by the input signal, one or more processing devices, and one or more transducers. The processing devices receive the input signal and generate an updated set of filter coefficients of the adaptive filter by separating the input signal into frequency subbands; determining for each subband, coefficients of a corresponding subband adaptive module; and combining the coefficients of multiple subband adaptive modules. Determining the coefficients of the corresponding subband adaptive module includes selecting a subset of a precomputed set of filter coefficients of the adaptive filter. The processing devices process a portion of the input signal using the updated set of filter coefficients of the adaptive filter to generate an output that destructively interferes with another signal traversing the path represented by the transfer function.

A control apparatus, that can expand a range in which noise generated in an unmanned flying object is reduced, is provided. The control apparatus acquires position information of one or more unmanned flying objects and noise information concerning first noises generated by the one or more unmanned flying objects. The control apparatus also acquires output region information indicating an output region of sound output from a speaker. The control apparatus calculates, using the position information, the output region information, and the noise information, second noises that reach the output region. The second noises are caused by the first noises which are generated by the one or more unmanned flying objects. The control apparatus generates opposite phase signals for outputting opposite phase sounds with respect to the calculated second noises, and causes the speaker to output sound on a basis of the generated opposite phase signals.

In a method for determining a response function of a noise cancellation enabled audio device, the audio device is placed onto a measurement fixture, wherein a loudspeaker of the audio device faces an ear canal representation of the measurement fixture. A first and a second response function between an ambient sound source and a test microphone located within the ear canal representation are measured while parameters of a noise processor of the audio device are set to a proportional transfer function with respective first and second gain factors being different from each other. A model response function is determined based on the first and the second response function and on the first and the second gain factor.

Various technologies described herein pertain to active noise cancellation in the interior of a vehicle. In exemplary embodiments, a microphone mounted on the vehicle outputs an audio signal indicative of noise emitted by a noise source. A computing system of the vehicle determines a position of the noise source based upon sensor signals output by sensors mounted on the vehicle. The computing system further determines a position of a passenger in the vehicle based upon a sensor mounted inside the vehicle. The computing system generates a complementary signal that is configured to attenuate the noise based upon the audio signal, the position of the noise source, and the position of the passenger. The complementary signal is then output by way of a speaker in the interior of the vehicle.

Embodiments are disclosed relating to an active noise reducing system and method for a headphone with a rigid cup-like shell which has an outer surface and an inner surface that encompasses a cavity with an opening. The system and method include picking up sound at least at three positions that are regularly distributed over the outer surface, and providing a first electrical signal that represents the picked-up sound. The system and method further include: filtering the first electrical signal to provide a second electrical signal, and generating in the opening of the cavity sound from the second electrical signal. Filtering is performed with a transfer characteristic that is configured so that noise that travels through the shell from beyond the outer surface to beyond the inner surface is reduced by the sound generated in the opening.

Various technologies described herein pertain to active noise cancellation in the interior of a vehicle. In exemplary embodiments, a microphone mounted on the vehicle outputs an audio signal indicative of noise emitted by a noise source. A computing system of the vehicle determines a position of the noise source based upon sensor signals output by sensors mounted on the vehicle. The computing system further determines a position of a passenger in the vehicle based upon a sensor mounted inside the vehicle. The computing system generates a complementary signal that is configured to attenuate the noise based upon the audio signal, the position of the noise source, and the position of the passenger. The complementary signal is then output by way of a speaker in the interior of the vehicle.

Personal speaker systems including headset and earbud systems may be configured to capture audio data using an in-ear microphone while a speaker outputs known audio signals into the ear canal. The system may generate an acoustic model of the compressed ear canal and ear drum of the listener and utilize the acoustic model to provide noise cancelation at the eardrum, modification to the audio to result in a more natural sound at the eardrum, and/or to measure leakage of the personal speaker system.

Two subsystems, each including a microphone, a speaker, a canceling sound-generating adder, an error-computing adder, and two adaptive filters and two auxiliary filters that accept two noises as input, are provided in correspondence with two cancellation positions. Each canceling sound-generating adder adds together the outputs from the adaptive filters and outputs the result to the speaker of each subsystem. Each error-computing adder adds together the output from the microphone of the subsystem and the output from the auxiliary filter of the subsystem, and the result is treated as the error of the adaptive filters of each subsystem. A transfer function is learned in advance and set in each auxiliary filter such that each error computed by each error-computing adder becomes zero (0) when a transfer function in which each noise is canceled at each cancellation position in a predetermined standard acoustic environment is set in each adaptive filter.

Active noise control system and methods are disclosed that include generating anti-noise that is configured to reduce or cancel noise occurring at a listening position in the ambiance of a seat with a backrest enclosing a hollow volume. Radiating the anti-noise from within the hollow volume of the backrest of the seat.

Various technologies described herein pertain to active noise cancellation in the interior of a vehicle. In exemplary embodiments, a microphone mounted on the vehicle outputs an audio signal indicative of noise emitted by a noise source. A computing system of the vehicle determines a position of the noise source based upon sensor signals output by sensors mounted on the vehicle. The computing system further determines a position of a passenger in the vehicle based upon a sensor mounted inside the vehicle. The computing system generates a complementary signal that is configured to attenuate the noise based upon the audio signal, the position of the noise source, and the position of the passenger. The complementary signal is then output by way of a speaker in the interior of the vehicle.