A method for feedforward noise cancellation in an enclosed space within a structure is provided. The method comprises placing a microphone array inside an inner surface of the enclosed space and conducting modal testing on an outside surface of the enclosed space, wherein the modal testing comprises multiple incoherent noise sources corresponding to locations of microphones in the microphone array. Noise generated by the modal testing is processed to create a number of acoustic mathematical models of the enclosed space. In response to incoherent noise within the enclosed space, a noise canceling signal is generated according to an output of the mathematical models.

An audio system may include a microphone configured to sense sound and generate an analog audio signal; an analog-to-digital convertor (ADC) configured to convert the analog audio signal to a digital audio signal having a first bit rate; a motion sensor configured to sense motion associated with the microphone and generate a motion signal representative of the motion associated with the microphone; a motion signal conversion module configured to convert the motion signal to a digital audio noise signal having a second bit rate synchronized with the first bit rate; and a noise suppression module configured to at least partially suppress the digital audio noise signal relative to the digital audio signal to generate a noise-suppressed digital audio signal.

An active noise control device includes a determination unit configured to determine whether an abnormality has occurred in an acceleration sensor based on a direct-current component of a reference signal acquired by the acceleration sensor attached to a vehicle, and a control unit configured to, when the determination unit determines that an abnormality has occurred in any of a plurality of the acceleration sensors, stop generation of the control signal based on the reference signal acquired by the acceleration sensor that has been determined to have the abnormality, and stop updating a filter coefficient of an adaptive filter configured to perform the filtering process on the reference signal acquired by the acceleration sensor that has been determined to have no abnormality.

An acoustic apparatus includes a sound-emitting unit that acoustically outputs a sound signal, at least one sensor that periodically detects accelerations of the user in three directions including a front-rear direction, a left-right direction, and an upper-lower direction, a vibration sound peak detection unit detecting a peak of a vibration sound based on a movement of the user when detection values of the accelerations in the front-rear direction, the left-right direction, and the upper-lower direction satisfy a predetermined condition, and a signal processing unit that determines whether a time difference at which the peak of the vibration sound is detected is periodic. When it is determined that the time difference is periodic, the signal processing unit sets a gain of a cancellation signal to be suppressed from the sound signal acoustically output from the sound-emitting unit based on the peak of the vibration sound.

Methods and systems are provided for an automatic noise control system. Automatic noise control includes evaluating an amplitude of an acceleration acting on an acceleration sensor and generating a reference signal representative of the amplitude of the acceleration, the acceleration being representative of unwanted noise sound generated by a noise source, filtering the reference signal with a noise control transfer function to generate an anti-noise signal, and converting with a loudspeaker the anti-noise signal into anti-noise sound.

An active noise control system selects one reference sensor providing a reference signal with the largest coherence to a noise signal, among a plurality of available reference sensors, as a first entry of a reference sensor set. After selecting the first entry, the active noise control system repeats a process in which a sensor capable of providing the largest information quantity to a current reference sensor set among remaining sensors is selected as a new entry of a reference sensor set, until a desired number of sensors is reached or a desired control level is reached. When the reference sensor set is determined, the active noise control system utilizes the entries of the reference sensor set to generates a noise control signal suitable for canceling the noise signal.

A sound control device and a method for controlling the sound control device in a vehicle. The method comprises obtaining an error signal indicating residual noise in the vehicle, and an audio signal; calculating magnitudes of low frequency components of the error signal; adjusting magnitudes of low frequency components of the audio signal according to the magnitudes of the low frequency components of the error signal; and outputting the adjusted audio signal through a speaker.

In at least one embodiment, a system for providing a frequency dependent dynamic leakage for noise cancellation is provided. The system includes a noise cancellation controller and a current limiter. The noise cancellation controller is programmed to perform noise cancellation in a vehicle based on a limited input signal. The current limiter is programmed to receive a reference signal from one of an accelerometer or a loudspeaker and to convert the reference signal from a time domain and into a frequency domain to limit the reference signal. The current limiter is further programmed to generate the limited input signal in response to limiting the reference signal.

A method of canceling road noise includes: receiving a first signal from an acceleration sensor disposed at a vehicle and a second signal from a microphone disposed at the vehicle; monitoring, based on the first and second signals, whether an abnormal event has occurred; determining, based on a result from monitoring whether the abnormal event has occurred, a plurality of parameter values for performing adaptive filtering; and performing, based on the determined parameter values, adaptive filtering to generating an output signal for noise canceling.

A method performed by a head-mounted wearable audio output device is provided. The audio output device is worn on a head of a user and includes at least one sensor. The device detects a user activity based on motion of the user's body using the at least one sensor. The devices detects an orientation of the head of the user is one of upward or downward using the at least one sensor. The devices controls at least one of: a level of attenuation applied to external noise or audio output based on the detected user activity and the detected orientation of the head of the user.