Provided is a technique for selecting a cancellation filter coefficient that can stably cancel noise for a user using a seat of an aircraft, an automobile, or the like. A cancellation filter coefficient selection apparatus includes: a recording unit configured to record cancellation filter coefficients; a seat position acquisition unit configured to acquire a position of a seat used by a user; and a cancellation filter coefficient selection unit configured to, from among the cancellation filter coefficients recorded in the recording unit, select a cancellation filter coefficient corresponding to the position of the seat as a cancellation filter coefficient to be used in filtering for generating a cancellation signal for cancelling noise at a position where quiet is desired, based on a reference signal output by a reference microphone configured to collect noise in a predetermined space. The reference microphone and a speaker for emitting sound based on the cancellation signal are installed on the seat, and positions of the reference microphone and the speaker in the predetermined space change accompanying movement of the seat.

A noise cancellation system for a vehicle, with a microphone for receiving noise and generating a corresponding noise signal; a loudspeaker for emitting an acoustic wave according to a cancellation signal to cancel the noise; a control unit comprising a memory and a controller; wherein the memory has a noise filter; and wherein the controller is configured to obtain at least a vehicle related information of the vehicle; to configure the noise filter based on the at least one vehicle related information; and to generate a cancellation signal based on the noise signal and the noise filter.

The present subject matter relates to systems and methods for selectively amplifying an acoustic signal in a closed environment. In an implementation, a plurality of acoustic signals may be received from within the closed environment. Frequency ranges corresponding to each acoustic signal may be obtained and compared to determine presence of at least one individual in the closed environment. Acoustic signals pertaining to the at least one individual may be analysed to detect occurrence of a physiological event. Based on the analysis, the acoustic signal may be recognized as a target signal, and the target signal may be amplified in the closed environment. Further, an interfering signal may be generated to cancel other acoustic signals within the closed environment.

An ambient-aware audio system reduces stationary noise and maintains dynamic environmental sound in a received input audio signal. The system includes a signal-to-noise ratio (SNR) estimator that estimates an a priori SNR and an a posteriori SNR, a gain function that uses the estimated SNRs as inputs to compute coefficients of a frequency domain noise reduction filter that uses the computed coefficients to filter a frame of the input audio signal to generate an output audio signal. The SNR estimator, gain function, and filter are configured to iterate over a plurality of frames of the input audio signal. The SNRs are estimated using the input audio signal and the output audio signal associated with one or more of the plurality of frames. The gain function is derived to minimize an expected value of differences between spectral amplitudes of the output audio signal and the input audio signal.

An active noise reduction system and method, and a storage medium are provided. In the system, a first signal acquisition circuitry acquires an external noise signal at a noise cancellation spot, and transmits the acquired external noise signal to a noise control system including a first frequency nonlinear transformation circuitry, a first filter circuitry and an inverter. The first frequency nonlinear transformation circuitry receives the external noise signal, and expands at least one target frequency band of the external noise signal based on a frequency nonlinear transformation mapping function to generate a first transformed external noise signal, the first filter circuitry filters the first transformed external noise signal to generate a filtered external noise signal, and the inverter performs inversion on the filtered external noise signal to generate a noise cancellation signal; and the signal output circuitry receives and outputs the noise cancellation signal to cancel an actual noise.

The headphones (10) comprise: a transducer (16) (12); an noise-canceling processing chain (30, 40) comprising: a microphone (31, 41); a noise-canceling processing filter (34, 44) which comprises in series: a stabilisation filter (34A, 44A) whose transfer function is substantially equal to the inverse of the transfer function of the processed secondary path, and a noise cancellation filter (34B, 44B) whose transfer function is a noise cancellation transfer function. The secondary path is formed between the transducer (16) and the eardrum, and the transfer function of the processed secondary path is the transfer function of the secondary path combined with the transfer functions of the processing components, excluding the processing filter (34, 44).

A method and system directed to controlling audio devices with active noise reduction. The system detects an instability condition in a first headphone; generates one or more control signals to adjust one or more ANR parameters of the first headphone using a first controller, wherein the one or more ANR parameters are adjusted to change the first headphone from a first ANR state to a second ANR state to mitigate the instability condition; and synchronizes the one or more ANR parameters of the first headphone with second headphone. In an example, the system returns the first headphone to the first ANR state after detecting that the first headphone was removed from an ear of a user at the first time and detecting that the first headphone was engaged with the ear at the second time.

A speaker and a microphone are provided to a helmet main body. A phase of a sound signal passing through a high pass filter is controlled by a first phase control section, and is amplified by a first amplification section. A phase of a sound signal passing through the low pass filter is controlled by a second phase control section, and is amplified by a second amplification section. These sound signals are synthesized by a synthesis section. A drive section drives the speaker according to a synthesized sound signal. A control section switches phase inversion processing/non-inversion processing of the phase control sections and controls an amplification factor of the amplification sections based on sound power of the sound signal.

A noise cancellation filter structure for a noise cancellation enabled audio device, in particular headphone, comprises a noise input for receiving a noise signal and a filter output for providing a filter output signal. A first noise filter produces a first filter signal by filtering the noise signal and a second noise filter produces a second filter signal by filtering the noise signal. The second noise filter has a frequency response with a non-minimum-phase, in particular maximum-phase. A combiner is configured to provide the filter output signal based on a linear combination of the first filter signal and the second filter signal.

In accordance with embodiments of the present disclosure, an adjustable equalization filter may have a response that generates an equalized source audio signal from a source audio signal to account for effects of changes in an electro-acoustical path of the source audio signal to a transducer. An equalizer coefficient control block may adapt the response of the adjustable equalization filter in response to changes in a response of a secondary path estimate filter for modeling the electro-acoustical path of a source audio signal through the transducer, wherein a response of the secondary path estimate filter is adapted in conformity with an error microphone signal indicative of the acoustic output of the transducer.