A noise-cancellation system , comprising: an accelerometer arranged and configured to detect acceleration indicative of a disturbance, wherein the accelerometer is also arranged and configured to generate a noise signal indicative of the disturbance when an absolute value of a derivative of the acceleration exceeds a threshold value; a controller arranged and configured to generate a noise-cancellation signal and transmit the noise-cancellation signal to a speaker , which transduces the noise-cancellation signal to acoustic energy; a level detector arranged and configured to receive the noise signal , calculate the absolute value of the derivative of the acceleration indicative of the disturbance from the noise signal , determine if the absolute value exceeds the threshold value, and set a noise signal output by the level detector to a zero value if the absolute value exceeds the threshold value; a reference sensor arranged and configured to detect residual noise resulting from the combination of the acoustic energy of the noise-cancellation signal and the disturbance, and to generate a reference sensor signal based on the detection of residual noise; an adaptive processing module configured to receive the reference sensor signal and the noise signal output by the level detector , and generate a filter update signal , wherein the filter update signal is set to a zero value if the absolute value exceeds the threshold value; and an adaptive filter having one or more filter coefficients, the adaptive filter configured to receive the filter update signal and adjust the one or more filter coefficients based on the filter update signal if the filter update signal exceeds a zero value. an accelerometer arranged and configured to detect acceleration indicative of a disturbance, wherein the accelerometer is also arranged and configured to generate a noise signal indicative of the disturbance when an absolute value of a derivative of the acceleration exceeds a threshold value; a controller arranged and configured to generate a noise-cancellation signal and transmit the noise-cancellation signal to a speaker , which transduces the noise-cancellation signal to acoustic energy; a level detector arranged and configured to receive the noise signal , calculate the absolute value of the derivative of the acceleration indicative of the disturbance from the noise signal , determine if the absolute value exceeds the threshold value, and set a noise signal output by the level detector to a zero value if the absolute value exceeds the threshold value; a reference sensor arranged and configured to detect residual noise resulting from the combination of the acoustic energy of the noise-cancellation signal and the disturbance, and to generate a reference sensor signal based on the detection of residual noise; an adaptive processing module configured to receive the reference sensor signal and the noise signal output by the level detector , and generate a filter update signal , wherein the filter update signal is set to a zero value if the absolute value exceeds the threshold value; and an adaptive filter having one or more filter coefficients, the adaptive filter configured to receive the filter update signal and adjust the one or more filter coefficients based on the filter update signal if the filter update signal exceeds a zero value. <EOS>