Mixing media files

Mixing individualized media content. When individualized media content is generated from separate media clips or files, mixing the separate media clips includes controlling the audio. The volume of the audio in each clip is determined and normalized with respect to other media clips as the individualized media content is mixed. This provides a consistent audio experience even when the media content is generated from multiple sources having different properties. When more than one track of audio is present, such as voice audio and background music, the volume of one track is lowered such that the other audio track is audible. The volume of the background music, for example, is reduced such that the subscriber can hear the instructions in the voice audio.