At enrollment, participants completed a simple sociodemographic form and were given detailed verbal and written instructions about operating the digital recorder and completing the 24-hour asthma dairy. The recorder was turned on during the enrollment meeting and the attached microphone was clipped to the free edge of the teen's shirt closest to the sternal notch. Participants recorded their breath sounds for the next 24 hours. During nighttime, participants placed the recorder and microphone on a surface close to the head of their bed for continuous recording. When privacy was desired, participants were instructed to pause and then restart the recorder later. Although participants were told not to alter their daily routine in any significant manner when recording, they were encouraged to find opportunities to record periods of time in a quieter environment with minimal talking and background noise, when feasible. Participants were required to provide a minimum of 10 hours of audio-recorded data. The asthma diary and the digital recorder were returned the following day.