Provided is a signal processing device that performs noise canceling by combining a feedforward method and a feedback method. A signal processing device includes: a correlation calculation unit that calculates a correlation between a first sound pickup signal by a first microphone installed outside a predetermined region and a second sound pickup signal by a second microphone installed in the predetermined region; a determination unit that determines the correlation; and a control unit that performs control based on a result of the determination. The control unit controls execution of signal processing for generating a cancellation signal to be output within the predetermined region from the first sound pickup signal and the second sound pickup signal or output of the cancellation signal.

An audio system for an ear mountable playback device comprises a speaker and an error microphone that is configured to sense sound being output from the speaker and ambient sound. The audio system further comprises a detection engine that is configured to determine a driver response between the speaker and the error microphone, and to estimate a leakage condition from the determined driver response.

In certain aspects, an active noise control (ANC) method and system for a headphone are disclosed. It is determined whether a music signal is played by a speaker of the headphone. Responsive to the music signal not being played by the speaker and a noise level of an ambient noise signal being greater than a noise threshold, a set of noise feedforward (FF) signals is obtained based on a set of FF microphone signals acquired by a set of FF microphones of the headphone. A noise feedback (FB) signal is obtained based on a first FB microphone signal acquired by a FB microphone of the headphone. A set of leakage monitoring parameters is obtained based on the set of noise FF signals and the noise FB signal. A set of FF filter parameters for a set of FF filters is adjusted based on the set of leakage monitoring parameters.

Noise abatement within a signal stream containing unwanted signal referred to as noise is performed by acquiring a digitized noise signal and using a digital processor circuit to subdivide the acquired noise signal into different frequency band segments and thereby generate a plurality of segmented noise signals. Then individually for each segmented noise signal, the processor shifts in time the segmented noise signal by an amount dependent on a selected frequency of the segmented noise signal to produce a plurality of shifted segmented noise signals. The precise time shift applied to each noise segment considers the frequency content of the segment and the system processing time. Individually for each segmented noise signal, amplitude scaling is applied. The shifted and amplitude-scaled segmented noise signals are then combined to form a composite anti-noise signal which is output into the signal stream to abate the noise through destructive interference.

The present disclosure presents a feedback active noise control system and strategy with online secondary-path modeling, and belongs to the technical field of active noise control. The linear prediction subsystem takes the residual noise as its input and separates the remaining sinusoidal noise from the broadband noise. The remaining sinusoidal noise is used effectively not only to update the controller but also to scale the auxiliary noise, while the broadband noise serves as a desired input of online secondary-path modeling subsystem. In this way, the coupling between the controller and the online secondary-path modeling subsystem is significantly mitigated, leading to both faster convergence and improved noise reduction performance. A practical scheme for refreshing the entire system is also developed to enhance its robustness against even abrupt changes with the secondary path or the primary noise. The present disclosure enhances the applicability of feedback active noise control in practical applications.

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 reducing noise within a vehicle cabin comprising at least one error sensor and at least one sound transducer, the method comprising: the at least one error sensor measuring at least one first noise at a first location; selecting at least one sound zone from a plurality of sound zones within the cabin for reducing noise in said at least one sound zone, based on a presence of a driver and passenger(s) within the cabin; estimating at least one second noise that would have been measured at a second location within the selected at least one sound zone, based on a primary transfer function describing a primary acoustic path from the first location to the second location; the at least one sound transducer generating at least one secondary noise for reducing the at least one second noise that would have been measured at the second location.

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.

According to an embodiment, a sound emitting apparatus includes a helical hollow tube and at least three sound wave sources. The helical hollow tube helically extends in a circumferential direction to form an annular shape as a whole. The first helical hollow tube includes a plurality of openings. The at least three sound wave sources are coupled to the first helical hollow tube and are configured to supply a sound wave to the first helical hollow tube.

A first input signal captured by one or more sensors associated with an ANR headphone is received. A frequency domain representation of the first input signal is computed for a set of discrete frequencies, based on which a set of parameters is generated for a digital filter disposed in an ANR signal flow path of the ANR headphone, the set of parameters being such that a loop gain of the ANR signal flow path substantially matches a target loop gain. Generating the set of parameters comprises: adjusting a response of the digital filter at frequencies (e.g., spanning between 200 Hz-5 kHz). A response of at least 3 second order sections of the digital filter is adjusted. A second input signal in the ANR signal flow path is processed using the generated set of parameters to generate an output signal for driving the electroacoustic transducer of the ANR headphone.