A media playback device has programmable signal processing capabilities and an input receiving signals representative of ambient noise. The media playback device identifies an output response characteristic and an attenuation characteristic of a set of headphones associated with the media playback device, predicts a property of audio output by the headphones at a user's ear based on the ambient noise input signal, the output response characteristic, and the attenuation characteristic of the headphones, predicts expected residual ambient noise at the user's ear, when wearing the headphones, derived from the ambient noise input signal and the attenuation characteristic, and modifies masking audio signals to be provided to the headphones such that they will mask the expected residual ambient noise at the user's ear.