A signal processing apparatus includes a signal processor configured to: generate a first noise reduction signal using an adaptive filter based on a signal output from a first input apparatus, and cause the generated first noise reduction signal to be output by a first output apparatus; and generate a second noise reduction signal using a feedback filter based on a signal output from a second input apparatus, and cause the generated second noise reduction signal to be output by a second output apparatus. The feedback filter has a fixed feedback coefficient. The first input apparatus is located at a first noise-cancellation target location in an environment, and the second input apparatus is located at a second noise-cancellation target location in the environment, which may be different from the first noise-cancellation target location.

A noise cancellation system with harmonic filtering for a vehicle audio system may include at least one input sensor configured to transmit reference signals, and at least one input sensor configured to transmit at least two narrowband input signals each of the input signals including harmonic noise. The system may include a processor being programmed to receive the reference signals, the reference signals including at least two narrowband reference signals, receive the narrowband input signals, apply a gain reference control to the reference signals to determine whether the frequencies of each of the reference signals are within a predefined range of another, and remove one of the reference signals in response to the frequencies of each of the reference signals being within the predefined range of another to prevent common harmonic content from presiding on both reference signals during the algorithm adaption.

[Object] To provide a structure that can effectively reduce a noise containing a component varying in characteristic.

[Solution] A signal processing apparatus including: a signal processing section configured to generate a first noise reduction signal using an adaptive filter on the basis of a signal output from a first input apparatus, and cause the generated first noise reduction signal to be output by a first output apparatus, and generate a second noise reduction signal using a fixed filter on the basis of a signal output from a second input apparatus, and cause the generated second noise reduction signal to be output by a second output apparatus.

A noise cancellation system with harmonic filtering for a vehicle audio system may include at least one input sensor configured to transmit reference signals, at least one input sensor configured to transmit a narrowband input signal and a broadband input signal, each of the narrowband input signal and broadband input signal including harmonic noise. The system may include a processor being programmed to receive the reference signals, the reference signals including a narrowband reference signal and a broadband reference signal, apply an adaptive filter to each of the reference signals, apply a secondary path to the input signals to generate antinoise signals, sum the antinoise signals broadcast over the secondary path and the primary noise signals to generate an error signal at the output sensor, and apply an adaptive filter to the error signal to remove harmonic noise to prevent cancelation of the harmonic noise.

An active noise cancellation system for reducing unwanted noise in a target area by attenuating a disturbance noise signal (d(n)), which is the remaining noise in the target area originated from an ambient noise signal (x(n)) present in the vicinity of the target area that is transferred to the target area via a main path described by a transfer function P(z)), the active noise cancellation system including a processing unit that implements an ANC-controller which is configured to provide a control signal (y(n)) for controlling a speaker in the target area in order to generate an acoustic signal (y(n)) that destructively overlaps with the disturbance noise signal (d(n)) and thereby attenuates the same.

A method of using an acoustic resonator including receiving at a first stage of a resonator an incoming acoustic wave. The method further includes resonating the incoming wave with a flexible membrane, a taper of the flexible membrane, and a cavity of a first stage, thereby producing synergistic effect on a resulting acoustic resonance. Additionally, the method includes transforming an acoustic energy associated with the incoming acoustic wave into an elastic energy, wherein the elastic energy is channeled through the flexible membrane, thereby reducing an intensity of the incoming acoustic wave and resulting in a first reduced incoming acoustic wave. Further the method includes transferring the first reduced incoming acoustic wave through a hole of a neck of the flexible membrane. The method also includes transferring a first pressure wave caused by a perturbation in the flexible membrane into a second stage, thereby producing a second acoustic wave.

Noise and vibration sensing includes generating with an acceleration sensor a sense signal representative of the acceleration that acts on the acceleration sensor, and processing the sense signal to provide a processed sense signal having an adjustable signal bandwidth and an adjustable signal dynamic. The signal bandwidth extends between a lowest frequency and a highest frequency of the sense signal, and the signal dynamic is the ratio between a maximum amplitude of the sense signal and an output noise floor generated by the acceleration sensor. Noise and vibration sensing further includes adjusting the signal bandwidth and the signal dynamic in accordance with a control signal so that the signal bandwidth increases when the signal dynamic decreases and vice versa.

A personal audio device, such as a wireless telephone, includes noise canceling that adaptively generates an anti-noise signal from a reference microphone signal and injects the anti-noise signal into the speaker or other transducer output to cause cancellation of ambient audio sounds. An error microphone is provided proximate the speaker to measure the output of the transducer in order to control the adaptation of the anti-noise signal and to estimate an electro-acoustical path from the noise canceling circuit through the transducer. The anti-noise signal is adaptively generated to minimize the ambient audio sounds at the error microphone. A processing circuit that performs the adaptive noise canceling (ANC) function also filters one or both of the reference and/or error microphone signals, to bias the adaptation of the adaptive filter in one or more frequency regions to alter a degree of the minimization of the ambient audio sounds at the error microphone.

Exemplary engine order and road noise control systems and methods include directly picking up road noise from a structural element of a vehicle to generate a first sense signal representative of the road noise, detecting harmonics of an engine of the vehicle to generate a second sense signal representative of the engine harmonics, and combining the first sense signal and the second sense signal to provide a combination signal representing the combination of the first sense signal and the second sense signal. The systems and methods further include broadband active noise control filtering to generate a filtered combination signal, and converting the filtered combination signal from the active noise control filtering into anti-noise and radiating the anti-noise to a listening position in an interior of the vehicle. The filtered combination signal is configured so that the anti-noise reduces the road noise and engine sound at the listening position.

Noise and vibration sensing includes generating with an acceleration sensor a sense signal representative of the acceleration that acts on the acceleration sensor, and processing the sense signal to provide a processed sense signal having an adjustable signal bandwidth and an adjustable signal dynamic. The signal bandwidth extends between a lowest frequency and a highest frequency of the sense signal, and the signal dynamic is the ratio between a maximum amplitude of the sense signal and an output noise floor generated by the acceleration sensor. Noise and vibration sensing further includes adjusting the signal bandwidth and the signal dynamic in accordance with a control signal so that the signal bandwidth increases when the signal dynamic decreases and vice versa.