Audio systems and methods are provided that receive a playback signal and produce an acoustic signal based upon the playback signal, and include microphone signal(s) for capturing and processing user voice signals. An echo reference signal is based upon the playback signal, and an echo canceler reduces echo components from the microphone signal(s). Functionality of the echo canceler is modified, such as by freezing an adaptive filter, in response to a non-linear condition in the audio playback, or a likelihood of such a non-linear condition.