1. A method, comprising: selecting a primary media item for playback on an electronic device; selecting a secondary media item for playback on the electronic device; and ducking the primary media item by a ducking value while the second media item is played based upon a desired relative loudness difference, such that the relative loudness difference is substantially maintained and such that the primary media item is played at a ducked loudness level during an interval of concurrent playback in which the primary and secondary media items are both played back simultaneously on the electronic device, wherein the primary media item is associated with a plurality of loudness values corresponding to a plurality of respective discrete time samples of the primary media item, and wherein the time at which the concurrent playback interval begins is determined based on a time sample corresponding to the selection of an optimal loudness value from the plurality of loudness values.