Methods for audio processing suitable for use with an earpiece are provided. A method includes delivering audio to an ear canal, measuring a residual background noise level within the ear canal, and adjusting the audio based on characteristics of the residual background noise level to maintain a natural audio level. A mixing of an ambient sound signal and an ear canal signal can be used to calculate the residual background noise level. The method can include compensating the residual measurement based on microphone sensitivities.