An open acoustic device (100) may include a fixing structure (120) configured to fix the acoustic device (100) near an ear of a user without blocking an ear canal of the user; a first microphone array (130) configured to acquire environmental noise (410); a signal processor (140) configured to: determine, based on the environmental noise, a primary route transfer function (420) between the first microphone array (130) and the ear canal of the user; estimate, based on the environmental noise and the primary route transfer function, a noise signal (430) at the ear canal of the user; and generate, based on the noise signal at the ear canal of the user, a noise reduction signal (440); and a speaker (150) configured to output, according to the noise reduction signal, a noise reduction acoustic wave (450), the noise reduction acoustic wave being configured to eliminate the noise signal.

An active control method for filtered reference affine projection sign algorithm based on variable step size includes: S1, acquiring impulse noise signals and transmitting the signals to control filters; S2, transmitting the impulse noise signals by the control filters to post filters; S3, generating cancellation signals of the impulse noise signals by the post filters according to the impulse noise signals and internal active control algorithms, and transmitting the cancellation signals to a speaker; S4, sending out the cancellation signal by the speaker to superimpose with the impulse noise signals to cancel the impulse noise signal. A convex combination structure and a variable step size strategy are adopted, and by adjusting step size coefficients in the control filter structure, convergence speed of algorithm is controlled, contradiction between convergence speed and steady-state error is coordinated, convergence performance of control algorithm to impulse noises is improved, and impulse noises are effectively controlled.

An active noise reduction device includes: a reference signal input terminal that receives a reference signal outputted by a reference signal source and having a correlation with noise in a space in an automobile, the reference signal source being attached to the automobile; a test signal source that outputs a test signal to a loudspeaker attached to the automobile, the loudspeaker being used to output a canceling sound for reducing the noise; and an anomaly determiner that determines whether the reference signal source has an anomaly, based on the reference signal inputted from the reference signal source to the reference signal input terminal when the test signal is outputted to the loudspeaker.

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.

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.

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.

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.

An audio system for a wearable device dynamically updates acoustic transfer functions. The audio system is configured to estimate a direction of arrival (DoA) of each sound source detected by a microphone array relative to a position of the wearable device within a local area. The audio system may track the movement of each sound source. The audio system may form a beam in the direction of each sound source. The audio system may identify and classify each sound source based on the sound source properties. Based on the DoA estimates, the movement tracking, and the beamforming, the audio system generates or updates the acoustic transfer functions for the sound sources.

A computing device, such as a headset, provides for selective sound level reduction or sound level amplification for sounds made in a local area. The computing device includes a speaker assembly and a controller. The controller receives an audio signal from a second computing device, such as a second headset, via a wireless connection with the computing device. The audio signal describes a sound made by a user of the second computing device. The audio signal arrives at the computing device prior to the sound. The controller determines an audio filter to selectively adjust an amplitude of the sound and applies the audio filter to the audio signal to generate audio content. The controller presents, via the speaker assembly, the audio content to a user such that the presented audio content combines with the sound to selectively adjust the amplitude of the sound.

An apparatus includes a sensor module configured for receiving sensed information indicative of a sensed signal. The sensed signal includes a source signal component and a source noise component. The apparatus also includes a reference module configured for reference information indicative of a reference signal. The reference signal also includes a reference noise component. The apparatus also includes a filter module configured as a fixed lag Kalman smoother. The filter module is configured for adaptively filtering the reference signal to generate an estimate of the source noise component. The apparatus also includes a processing module configured for calculating an output signal based on the sensed signal and the estimate of the source noise component. The apparatus also includes an interface module configured for transmitting an indication of the output signal. The filter module is further configured for, based on the output signal, tuning the Kalman smoother.