An integrated circuit implementing at least a portion of a personal audio device includes an output including an anti-noise signal, a reference microphone input, an error microphone input, and a processing circuit. The processing circuit implements an adaptive filter having a response that generates the anti-noise signal from the reference microphone signal to reduce the presence of the ambient audio sounds heard by the listener, wherein the processing circuit implements a coefficient control block that shapes the response of the adaptive filter in conformity with the error microphone signal and the reference microphone signal by adapting the response of the adaptive filter in accordance with a calculated narrow-band-to-full-band ratio, wherein the narrow-band-to-full-band ratio is a function of a narrow¬ band power of the reference microphone signal divided by a full-band power of the reference microphone signal.