A method for playing audio on a mobile device, the method comprising the steps of: a component of a digital work initiating a request for audio data during a rendering of the digital work, the digital work including video data; in response to the request, receiving the audio data; while continuing the rendering of the digital work on the mobile device, suspending playback of first audio data currently playing on the mobile device and playing the received audio data on the mobile device; when the received audio data stops playing continuing with the rendering of the digital work on the mobile device and resuming playback of the first audio data previously playing on the mobile device; detecting a current mobile device volume output level before the component of the digital work initiates the request for audio data; if the detected volume output level is below a predetermined threshold then preventing the request and playback of the audio data until the mobile device volume output level is at or above the predetermined threshold, where the predetermined threshold is an audio level high enough to be heard by a user of the mobile device; if the mobile device volume is at or above the predetermined threshold then starting to monitor how much of the audio data has been played back; reporting the monitored playback amount in time, percentage and/or reaching a quartile milestone, and reporting when the system audio level is muted and unmuted using an event tracker within an audio file containing the audio data, wherein the component carries out the monitoring and reporting steps; and using the reported playback amount to select audio for sending to the mobile device. a component of a digital work initiating a request for audio data during a rendering of the digital work, the digital work including video data; in response to the request, receiving the audio data; while continuing the rendering of the digital work on the mobile device, suspending playback of first audio data currently playing on the mobile device and playing the received audio data on the mobile device; when the received audio data stops playing continuing with the rendering of the digital work on the mobile device and resuming playback of the first audio data previously playing on the mobile device; detecting a current mobile device volume output level before the component of the digital work initiates the request for audio data; if the detected volume output level is below a predetermined threshold then preventing the request and playback of the audio data until the mobile device volume output level is at or above the predetermined threshold, where the predetermined threshold is an audio level high enough to be heard by a user of the mobile device; if the mobile device volume is at or above the predetermined threshold then starting to monitor how much of the audio data has been played back; reporting the monitored playback amount in time, percentage and/or reaching a quartile milestone, and reporting when the system audio level is muted and unmuted using an event tracker within an audio file containing the audio data, wherein the component carries out the monitoring and reporting steps; and using the reported playback amount to select audio for sending to the mobile device.