An earphone includes a loudspeaker, a microphone, a housing supporting the loudspeaker and microphone, and ear tip surrounding the housing and configured to acoustically couple both the loudspeaker and the microphone to an ear canal of a user, and to acoustically close the entrance to the user's ear canal. A processor provides output audio signals to the loudspeaker, receives input audio signals from the microphone, extracts a rate of respiration from the input audio signals, adjusts the output audio signals based on the extracted rate of respiration, and provides the adjusted output audio signals to the loudspeaker.