This phenomenon has multiple aspects:
- The sound of music from an unidentifiable source, usually near but sometimes farther away from the listener. The music may appear to be played by a single instrument or an entire band. Usually the songs are not contemporary, supporting the claim the sound is not electronically produced, i.e. coming from a modern radio station.
- A separate musical phenomenon involves an investigator who plays music relating to the era when a location was occupied which then produces heightened, observed paranormal activity (e.g era cues).
- Another aspect of this phenomenon is the occurrence of a song (with established ties to a deceased person) which plays on a radio in a synchronistic manner in relation to other events.