Earworms consist of songs mentally playing back beyond when I'm hearing them, and they have long plagued me, to the point that they were the main factor in my judgment that music is harmful. More recently, I've noticed patterns in how these earworms work, and some power to consciously control them. The apparent change could've come from mind-altering meditation, or other brain development. Or maybe my earworms always worked like this, and it's only now that I bothered to look.

Such discoveries prompted a self-experiment on how harmful music is, if at all.

Other people's minds probably experience earworms differently, if at all, especially if even my self-of-a-couple-years-ago may have experienced earworms so differently. If you've examined these mental mechanics to similar depth, and found different results, I would like to hear about it.

The majority of the time, there is some sound-pattern playing in my mind from memory. Usually, this is music, but sometimes it's something else, such as a chant I've heard recited hundreds of times. I've noticed some factors which affect whether such sound-patterns play at all.

• Music playing around me usually shuts up my recall for anything other than that current song.
• Heavy noise — more so if rhythmic, less so if verbal — seems also to suppress earworms.
• Meditation eventually turns them off, but they often stay on longer than any other form of thought.
• Earworms become more common during showers, and less common for a bit after I finish.
• Sometimes I can just shut off playback by sheer force of will, but sounds always return after some time.

There are also some empirical laws around which sound-pattern plays back at any given time. If a change to the environment or my willpower shuts up an earworm, but the change later reverts, the new earworm will usually be either the same song that was playing before, or an arbitrary one.

By "arbitrary", I mean that the song arose without any process I understand. Those cases are the most annoying. Some small set of songs, changing on the scale of days or weeks, are the most common arbitrary earworms at any given time. As I write this, the main one is Local Boys (Senthilkumar, 2013).

Hearing a fragment of a song often makes the rest start playing in my mind, after the fragment ends in the outside world. Seeing, hearing, or thinking of something related to a song — even as little as a keyword in the title — can make the apposite song accidentally return to my mind.

Given the title, or a unique description, of a song I already know, I can deliberately recall how it goes, distinctly from experiencing it as an earworm. If my mind is quiet, that song usually becomes a new earworm. If an earworm already plays, that song can become the new earworm, with extra mental effort.

Given a partial description of a song, I can trivially summon a possible match from the depths of my memory. This matching process is very subconscious, and is occasionally outright wrong.

The matched song becomes my new earworm, usually even if one was already present.