An audio system for an ear mountable playback device comprises a compensation filter configured to generate a third compensation signal by applying filter operations to an audio signal, and an error compensation unit configured to generate a compensated error signal on the basis of the third compensation signal and a disturbed audio signal from an error microphone. The audio system further comprises a first noise filter configured to be adapted based on the compensated error signal, and a detection unit configured to estimate the acoustic leakage condition on the basis of the first noise filter or of the disturbed audio signal and an audio output signal. The compensation filter is configured to be adapted based on the acoustic leakage condition.

An active noise cancelling system (20) comprising: an earphone (8′) comprising: an electro-acoustic driver (11); and at least one sensing microphone (12, 13); tunable active noise cancelling circuitry (7) operative to receive a signal from the at least one sensing microphone (12, 13), the tunable active noise cancelling circuitry (7) being pre-configured in a standard tuning for a reference ear and comprising at least one noise-control filter (14, 15); and a tuning module (24) operative to configure the earphone (8′) for an individual wearer by: comparing acoustic coupling of the earphone (8′) to the individual wearer's ear with acoustic coupling to the reference ear to determine a deviation in acoustic coupling; and using the determined deviation in acoustic coupling to modify the tunable active noise cancelling circuitry (7) by a predetermined degree based on the determined deviation in acoustic coupling.

A fan control system applied to N fans inside a computer system is disclosed, comprising: a main microphone, a control circuitry, a wave generation circuitry and a number N of fan controllers. The control circuitry calculates a basic frequency value according to a temperature inside the computer system, and continuously updates a parameter by any known optimization algorithm according to a main audio signal from the main microphone. The wave generation circuitry generates N square waves according to the basic frequency value and the parameter. The N fan controllers respectively form and transmit N modulation signals to the N fans according to the N square waves and N tachometric signals from the N fans. The parameter is one of a frequency variation and a set of phase differences, and the N square waves have the same frequency.

Sound reduction includes producing an error signal representative of sound present in a target space, producing a reference signal corresponding to undesired sound present in the target space, and producing, based on the reference signal and the error signal a cancelling output signal representative of the undesired sound present in the target space. The method further includes producing, based on the cancelling output signal, sound to destructively interfere with the undesired sound present in the target space, and limiting the amplitude or power of at least one of the reference signal, the error signal and the cancelling output signal if a first condition is met, the at least one signal under examination is at least one of the reference signal, the error signal and the cancelling output signal, and fully or partially suspending the active noise controller update mechanism if a second condition is met.

A noise cancellation system for cancelling sounds within a vehicle. The noise cancellation system includes microphones, a camera, a controller, and speakers. The microphones are disposed adjacent to occupant locations, and configured to generate microphone signals representative of noise sounds and cancellation audio sounds. The camera is configured to generate a video signal that captures head configurations of the occupants. The controller is configured to receive rotor control signals, calculate hearing locations based on tracking data of the head configurations of the occupants, and generate a speaker signals based on the hearing locations, the microphone signals, and the rotor control signals. The speakers are configured to generate the cancellation audio sounds. The cancellation audio sounds attenuate the noise sounds.

Embodiments of active noise control (ANC) headphones and operating methods thereof are disclosed herein. In one example, a headphone includes a speaker, an internal microphone, and a processor. The speaker is configured to play an audio of interest based on an audio source signal. The internal microphone is configured to obtain a mixed audio signal including a noise signal and the audio of interest played by the speaker. The processor is configured to determine a first current system parameter of the headphone based on the mixed audio signal at a first time point, and determine if the first current system parameter of the headphone is higher than a predetermined threshold to determine if the headphone is worn by a user.

A cooperative control unit is configured to cause a muffled sound control signal processing unit to start feedforward signal processing, and set, when a secondary path filter has converged, a narrow band noise control signal processing unit to the converged secondary path filter and cause the narrow band noise control signal processing unit to start feedback signal processing.

A computer-implemented method for determining whether the noise floor of a sensor is deviated from an expected value, comprising the steps of: receiving a sensor signal from a sensor; determining a plurality of power spectral densities from a plurality of successive frames of samples of the sensor signal, each of the plurality of power spectral densities being determined from a respective frame of the plurality of successive frames, each power spectral density being comprised of a plurality of frequency bins, each frequency bin being associated with a power of the respective frame at the frequency of the respective frequency bin, wherein each successive frame of the plurality of successive frames differs by at least one sample; identifying a minimum power of the plurality of power spectral densities; and determining whether the minimum power exceeds a threshold value.

A hybrid ANC system that can allow a feedback microphone to receive the same external noise as a feedforward microphone. A processor can generate an anti-noise signal based on what both microphones received to cancel a broader range of frequencies of the external noise.

The invention relates to an adaptive active noise cancellation apparatus and an audio playback system using the same. The adaptive active noise cancellation apparatus shapes an error signal and a noise signal according to a shape of an ideal noise. After that, the shaped noise signal and the shaped error signal are sent into a parameter adjusting unit to perform an adaptive parameter adjustment. Thus, the adaptive noise filter unit is not only can adaptively suppress noise and minimize the error signal, but also can suppress specific frequencies that are sensitive to the human ear.