A method for tuning filter parameters of a noise cancellation enabled audio system with an ear-mountable playback device comprising a speaker and a feedback noise microphone located in proximity to the speaker comprises provision of acoustic transfer functions between the speaker and the feedback noise microphone, between the speaker and an eardrum, between an ambient sound source and the eardrum and between the ambient sound source and the feedback noise microphone. The parameters of a feedback filter function, which is designed to process a feedback noise signal, are tuned. A noise cancellation performance of the audio system at the eardrum is determined based on each of the acoustic transfer functions and on the feedback filter function.

Methods for calibrating active noise-cancelling headphones, including placing the active noise-cancelling headphones on a measuring device; exciting the active noise-cancelling filter; measuring one or more relevant transmission pathways selected from x(n), m(n), and p(n) for feedforward and/or h(n) for feedback; defining at least one goal function for feedforward or feedback; calculating a complementary function for the defined goal function for at least one branch of the active noise-cancelling filter; calculating an impulse response of the complementary function from the measurements of the relevant transmission pathways; approximating operating parameters for the active noise-cancelling filter using the Prony method; and implementing the approximated operating parameters in the active noise-cancelling filter on the signal processor in order to create an approximated complementary active noise-cancelling filter, thereby calibrating the active noise-cancelling headphones.

In an active noise reducing headphone, a signal processor applies filters and control gains of both the feed-forward and feedback active noise cancellation signal paths. The signal processor is configured to apply first feed-forward filters to the feed-forward signal path and apply first feedback filters to the feedback signal path during a first operating mode providing effective cancellation of ambient sound, and to apply second feed-forward filters to the feed-forward signal path during a second operating mode providing active hear-through of ambient sounds with ambient naturalness.

A method for generating an active noise reduction filter includes: obtaining a physically noise-reduced signal, the physically noise-reduced signal being a signal received by a feedback microphone after a noise signal passes through an earphone, obtaining a mixed signal, the mixed signal being a signal received by the feedback microphone when the same noise signal is played and the earphone plays a through signal in a through state, calculating an input signal according to the mixed signal and the physically noise-reduced signal, performing adaptive filtering on the input signal and the physically noise-reduced signal according to an adaptive filtering algorithm to obtain a transfer function, and generating an active noise reduction filter according to the transfer function.

To reduce engine noise in the cabin of an aircraft a plurality of error microphones is deployed at predetermined locations within the cabin to produce error microphone response signals associated with the engine noise in the cabin. Engine vibration inputs are obtained from sensors coupled to the aircraft engines. A processor is used to code the error microphone response signals into an encoded modal response in the cabin through a coding matrix. A processor is used to apply an adaptive filter to determine a plurality of modal signals needed to cancel the encoded modal response in the cabin. A processor is used to decode the modal signals into speaker input signals through a decoding matrix. Speaker input signals are then sent to a plurality of speakers to reduce the engine noise in the cabin.

For example, a controller of an Active Acoustic Control (AAC) system may be configured to process input information, the input information including AAC configuration information corresponding to a configuration of AAC in a sound control zone; a plurality of noise inputs representing acoustic noise at a plurality of noise sensing locations; and a plurality of residual-noise inputs representing acoustic residual-noise at a plurality of residual-noise sensing locations within the sound control zone. For example, the controller may determine a sound control pattern to control sound within the sound control zone based on the AAC configuration information, the plurality of noise inputs, and the plurality of residual-noise inputs. For example, the controller may output the sound control pattern to a plurality of acoustic transducers.

A signal processing apparatus is configured to preprocess a sound wave signal and output a processed audio signal through an electromagnetic wave. The signal processing apparatus includes: a receiving unit, configured to receive at least one sound wave signal; a conversion unit, configured to convert the at least one sound wave signal to at least one audio signal; a positioning unit, configured to determine position information related to the at least one sound wave signal; a processing unit, configured to determine a sending time point of at least one audio signal based on the position information and a first time point, where the first time point is a time point at which the receiving unit receives the at least one sound wave signal; and a sending unit, configured to send the at least one audio signal through the electromagnetic wave.

Methods and systems are provided for an automatic noise control system. Automatic noise control includes evaluating an amplitude of an acceleration acting on an acceleration sensor and generating a reference signal representative of the amplitude of the acceleration, the acceleration being representative of unwanted noise sound generated by a noise source, filtering the reference signal with a noise control transfer function to generate an anti-noise signal, and converting with a loudspeaker the anti-noise signal into anti-noise sound.

Provided is an active acoustic control program that can reduce noise in a vehicle interior irrespective of the vehicle type, due to being installed in a device that is easily available to anyone. This active acoustic control program is downloaded using a communicator that transmits and receives data to and from a server, and this program causes a computation process device to execute a process for generating a control signal that causes a canceling sound to be outputted from a speaker provided in an interior of a vehicle in order to reduce noise in the vehicle interior. Said program is provided with an adaptive notch filter that processes a reference signal as an adaptive signal to generate a control signal, and a control filter coefficient update unit that continuously updates a filter coefficient of the adaptive notch filter so that an error signal is minimized.

A system and method for adaptive active noise reduction measure the acoustic response for each user to adaptively adjust and customize the ANR operation using adaptive filters to correct for any differences between the measured response and a targeted response. The system and method of various embodiments incorporate a closed loop control system with a feedforward input. The acoustic measurement and adaptation procedure is performed to adapt or tune at least one of the closed loop and feedforward control loops to provide adaptive ANR customized for each user and current ambient environment.