Stability is provided in an active noise reduction (ANR) headphone by measuring a sound field to generate an input signal, filtering and applying a variable gain to the input signal to produce a first filtered signal using a first filter and a variable gain amplifier in an ANR signal pathway, outputting the filtered signal, and simultaneously with outputting the first filtered signal, sampling a signal at a point in the ANR signal pathway and filtering the sampled signal using a second filter to produce a second filtered signal. The second filtered signal is compared to a threshold, and if the comparison finds that the second filtered signal is greater than the threshold signal, the gain of the variable gain amplifier is changed to attenuate the first filtered signal. The second filter applies different gains, different by at least 10 dB, in different frequency ranges between 10 Hz and 10 kHz.