Abstract: A noise-cancellation system includes a noise-cancellation filter in communication with at least one speaker, the noise-cancellation filter generating a noise-cancellation signal that, when actuated by the at least one speaker, cancels noise within at least one cancellation zone; and an amplifier disposed between the noise-cancellation filter and the speaker, the amplifier applying a first scaling gain to the noise-cancellation signal and outputting an scaled noise-cancellation signal, the scaled noise-cancellation signal being a linear reduction of the noise-cancellation signal when the first scaling gain is less than unity, wherein the first scaling gain is set to less than unity in response to a signal representative of the noise-cancellation signal exceeding a threshold.

Abstract: A vehicle-implemented, adaptive noise-cancellation system responsive to entertainment audio is provided. The noise-cancellation system uses reference signal from a reference sensor, such as an accelerometer, to generate a noise-cancellation signal to destructively interfere with road noise in the vehicle cabin. A first set of entertainment audio thresholds triggers the system to enable or disable adaptation of an adaptive filter of the noise-cancellation system. A second set of entertainment audio thresholds triggers the system to enable, attenuate, or disable the noise-cancellation signal. As the entertainment audio increases, the system first disables the adaptation of the adaptive filter, then attenuates the noise-cancellation signal, then completely disables the noise-cancellation signal.

Abstract: Various implementations include audio devices and methods for noise reduction control in wearable audio devices and/or vehicle audio systems. Certain implementations include a non-occluding wearable audio device having: at least one electro-acoustic transducer; at least one microphone; and a control system coupled with the at least one electro-acoustic transducer and the at least one microphone, the control system programmed to: adjust an active noise reduction (ANR) setting for audio output to the at least one electro-acoustic transducer in response to detecting use of the non-occluding wearable audio device in a vehicle.

Abstract: Noise cancellation systems and methods are provided that generate an anti-noise signal configured to destructively interfere with noise in a cancellation zone. The systems and methods receive a signal representative of the noise in the cancellation zone. The signal is analyzed to identify a frequency to be reduced in the cancellation zone, and the signal is down converted to place the identified frequency at baseband. A baseband anti-noise signal is generated based upon the down converted signal. The baseband anti-noise signal is up converted to the identified frequency to produce an anti-noise signal having components at the identified frequency, and the anti-noise signal is provided to be transduced into an acoustic signal.

Abstract: A vehicle-implemented, adaptive noise-cancellation system responsive to entertainment audio is provided. The noise-cancellation system uses reference signal from a reference sensor, such as an accelerometer, to generate a noise-cancellation signal to destructively interfere with road noise in the vehicle cabin. A first set of entertainment audio thresholds triggers the system to enable or disable adaptation of an adaptive filter of the noise-cancellation system. A second set of entertainment audio thresholds triggers the system to enable, attenuate, or disable the noise-cancellation signal. As the entertainment audio increases, the system first disables the adaptation of the adaptive filter, then attenuates the noise-cancellation signal, then completely disables the noise-cancellation signal.

Abstract: A vehicle-implemented, adaptive noise-cancellation system responsive to entertainment audio is provided. The noise-cancellation system uses reference signal from a reference sensor, such as an accelerometer, to generate a noise-cancellation signal to destructively interfere with road noise in the vehicle cabin. A first set of entertainment audio thresholds triggers the system to enable or disable adaptation of an adaptive filter of the noise-cancellation system. A second set of entertainment audio thresholds triggers the system to enable, attenuate, or disable the noise-cancellation signal. As the entertainment audio increases, the system first disables the adaptation of the adaptive filter, then attenuates the noise-cancellation signal, then completely disables the noise-cancellation signal.

Abstract: A vehicle-implemented noise-cancellation system, includes: a noise-cancellation system disposed in a vehicle, the noise-cancellation system comprising an adaptive filter being adjusted according to a reference signal and an error signal, the adaptive filter outputting a noise-cancellation signal, which, when transduced into a noise-cancellation audio signal by a speaker, cancels road noise within at least one zone within a cabin of the vehicle; and an adjustment module configured to vary a power of the noise-cancellation signal or a rate of adaptation of the adaptive filter from a first value to a second value, passing through at least one intermediate value between the first value and the second value, based on a time-varying signal indicative of a signal-to-noise ratio of the reference signal with respect to a first criterion.

Abstract: Noise cancellation systems and methods are provided that receive a reference signal representative of a noise to be reduced and provide a noise cancellation signal based upon the reference signal. Some examples include a feedback signal representative of a residual noise in the environment. At least one of the reference signal, the noise cancellation signal, or the feedback signal is filtered to remove components based upon a rotational rate of a rotating equipment associated with the environment, such as an engine of a vehicle. Accordingly, the noise cancellation system may not interfere with sounds related to the engine.

Abstract: A noise-cancellation system includes a noise-cancellation filter in communication with at least one speaker, the noise-cancellation filter generating a noise-cancellation signal that, when actuated by the at least one speaker, cancels noise within at least one cancellation zone; and an amplifier disposed between the noise-cancellation filter and the speaker, the amplifier applying a first scaling gain to the noise-cancellation signal and outputting an scaled noise-cancellation signal, the scaled noise-cancellation signal being a linear reduction of the noise-cancellation signal when the first scaling gain is less than unity, wherein the first scaling gain is set to less than unity in response to a signal representative of the noise-cancellation signal exceeding a threshold.

Abstract: Detecting a divergence in an adaptive system includes the steps of determining a power of a component of an error signal at a first frequency, the component being correlated to a noise-cancellation signal, the noise-cancellation signal being produced by an adaptive filter and being configured to cancel noise within a predetermined volume when transduced into acoustic signal, wherein the error signal represents a magnitude of a residual noise within the predetermined volume; determining a time gradient of the power of the component of the error signal; and comparing a metric to a threshold, wherein the metric is based, at least in part, on a value of the time gradient of the power of the component of the error signal over a period of time.

Abstract: Detecting a divergence in an adaptive system includes the steps of determining a power of a component of an error signal at a first frequency, the component being correlated to a noise-cancellation signal, the noise-cancellation signal being produced by an adaptive filter and being configured to cancel noise within a predetermined volume when transduced into acoustic signal, wherein the error signal represents a magnitude of a residual noise within the predetermined volume; determining a time gradient of the power of the component of the error signal; and comparing a metric to a threshold, wherein the metric is based, at least in part, on a value of the time gradient of the power of the component of the error signal over a period of time.

Abstract: A vehicle-implemented, adaptive noise-cancellation system responsive to entertainment audio is provided. The noise-cancellation system uses reference signal from a reference sensor, such as an accelerometer, to generate a noise-cancellation signal to destructively interfere with road noise in the vehicle cabin. A first set of entertainment audio thresholds triggers the system to enable or disable adaptation of an adaptive filter of the noise-cancellation system. A second set of entertainment audio thresholds triggers the system to enable, attenuate, or disable the noise-cancellation signal. As the entertainment audio increases, the system first disables the adaptation of the adaptive filter, then attenuates the noise-cancellation signal, then completely disables the noise-cancellation signal.

Abstract: Noise cancellation systems and methods are provided that generate an anti-noise signal configured to destructively interfere with noise in a cancellation zone. The systems and methods receive a signal representative of the noise in the cancellation zone. The signal is analyzed to identify a frequency to be reduced in the cancellation zone, and the signal is down converted to place the identified frequency at baseband. A baseband anti-noise signal is generated based upon the down converted signal. The baseband anti-noise signal is up converted to the identified frequency to produce an anti-noise signal having components at the identified frequency, and the anti-noise signal is provided to be transduced into an acoustic signal.

Abstract: A vehicle-implemented noise-cancellation system, includes: a noise-cancellation system disposed in a vehicle, the noise-cancellation system comprising an adaptive filter being adjusted according to a reference signal and an error signal, the adaptive filter outputting a noise-cancellation signal, which, when transduced into a noise-cancellation audio signal by a speaker, cancels road noise within at least one zone within a cabin of the vehicle; and an adjustment module configured to vary a power of the noise-cancellation signal or a rate of adaptation of the adaptive filter from a first value to a second value, passing through at least one intermediate value between the first value and the second value, based on a time-varying signal indicative of a signal-to-noise ratio of the reference signal with respect to a first criterion.

Abstract: A road noise-cancellation system, comprising: an actuator disposed in a vehicle cabin; a controller comprising a processor and non-volatile memory, the controller being programmed to: generate a noise-cancellation signal with a noise-cancellation filter including a first plurality of coefficients, the noise-cancellation signal being based on the first plurality of coefficients, the noise-cancellation signal being transduced by the actuator to generate a noise-cancellation audio signal based on the noise-cancellation signal, the noise-cancellation audio signal destructively interfering with an undesired noise in a noise-cancellation zone; adjust the first plurality of coefficients of the noise-cancellation filter based on one or more input signals to provide a second plurality of coefficients; store the second plurality of coefficients in the non-volatile memory during a shutdown sequence or at the end of an interval; and restore the second plurality of coefficients from non-volatile memory to the noise-cancel

Abstract: A noise-cancellation method, comprising the steps of: receiving a value from a noise sensor at a time step; storing the received value in a buffer, the buffer having a length, the buffer further storing a number of additional values, wherein an end value is removed from the buffer to accommodate the received value; providing a previously-computed result, wherein the previously-computed result represents the sum of the square of the values stored in the buffer at a previous time step; adding a square of the received value to the previously-computed result and subtracting a square of the end value from the sum of the received value and the previously computed value in order to yield a newly-computed result and updating a plurality of coefficients of an adaptive filter according to, in part, the value of the newly-computed result.

Abstract: A road noise-cancellation system, comprising: an actuator disposed in a vehicle cabin; a controller comprising a processor and non-volatile memory, the controller being programmed to: generate a noise-cancellation signal with a noise-cancellation filter including a first plurality of coefficients, the noise-cancellation signal being based on the first plurality of coefficients, the noise-cancellation signal being transduced by the actuator to generate a noise-cancellation audio signal based on the noise-cancellation signal, the noise-cancellation audio signal destructively interfering with an undesired noise in a noise-cancellation zone; adjust the first plurality of coefficients of the noise-cancellation filter based on one or more input signals to provide a second plurality of coefficients; store the second plurality of coefficients in the non-volatile memory during a shutdown sequence or at the end of an interval; and restore the second plurality of coefficients from non-volatile memory to the noise-cancel

Abstract: A noise-cancellation method, comprising the steps of: receiving a value from a noise sensor at a time step; storing the received value in a buffer, the buffer having a length, the buffer further storing a number of additional values, wherein an end value is removed from the buffer to accommodate the received value; providing a previously-computed result, wherein the previously-computed result represents the sum of the square of the values stored in the buffer at a previous time step; adding a square of the received value to the previously-computed result and subtracting a square of the end value from the sum of the received value and the previously computed value in order to yield a newly-computed result and updating a plurality of coefficients of an adaptive filter according to, in part, the value of the newly-computed result.

Abstract: A system and method for reducing or eliminating undesirable acoustic artifacts when a vehicle is struck by road debris. The method includes generating a noise signal representative of a first acceleration detected by an accelerometer of a vehicle caused by a disturbance and generating a noise-cancellation signal via a controller within the vehicle. Residual noise resulting from the combination of the acoustic energy of the noise-cancellation signal and the disturbance is detected by a reference sensor, which generates a reference sensor signal based on the residual noise. The reference sensor signal is transmitted to an adaptive processing module to adapt filter coefficients. A second acceleration is detected by the accelerometer and a level detector calculates the absolute value of a derivative of the second acceleration. If the absolute value exceeds a threshold value, adjustment of the filter coefficients is prevented.