An acoustic noise cancellation (ANC) process is performed during in-the-field use of a personal listening audio device, using a control filter to produce anti-noise by the device. The process includes computing an S_hat filter that estimates a signal path between an earpiece speaker of the device and an error microphone that are at a user's ear. A response associated with the computed S_hat filter is compared to a predetermined response that is stored in the device. The control filter is adjusted in accordance with the comparison. Other embodiments are also described and claimed.