Why is the length of a song in much modern music between 3 and 4 minutes?
One of our definition questions. This intrigued me because there are a lot of possible answers and I don't know if it's been investigated.
Is it simply convention? Is there some sort of psychological appeal/affect of this length and has it been studied, or does it just sort of seem to work? Has it been impacted by technology like radio, DJing, etc.?
I think evidence should be provided that most modern music is between 3-4 minutes long. Perhaps, as mentioned in some of the answers, radio edits are 3-4 minutes long, but I'm not sure most songs in general are.
@pacoverflow I don't think there is any argument that "much" modern music is approximately that length, which is why I worded it that way rather than saying "most songs in general". This isn't Skeptics, I don't think I need to provide proof of a claim in order to ask a question.
I agree with Matthew; but regardless, the Vox article linked in my answer does provide that evidence; though it does not provide exact methodology (and I, for one, have some questions about it) I imagine it's good enough for this purpose.
Because it is bound to the over-the-years optimized price of radio broadcast similar to Moore's law. They call it a head-to-head calculation. Per second time was pretty expensive on the radio. Then internet killed that economy but habit stayed.
I used to work at a radio station that played songs from the '50s onwards. Many of the older songs were only 1-2 minutes long! The average length increased as the music became more recent.
In addition to the other answers provided here, many point to the development of the medium for popular songs. Early recordings were made primarily on 78s, with the two most common sizes being 10" and 12"; the former having a maximum lengh of ~3 minutes, while the latter having a length of ~4-5 minutes. (Source.) The 78s were popularly replaced by 45s (created in 1949), which had similar limitations.
This Vox article has a good overview, containing this (unsourced) assertion:
For a band to get its songs played on the radio, it needed to have a 45. Artists complied. This invented what was known as the "single," for a record containing a single song. The 45 record was cheaper for Americans to buy than a full album and easier for radios to share, making the single in many ways the bedrock of American music.
When someone pointed out to the Beatles that radio stations were unlikely to play Hey Jude due to its length, they apparently said something like "they'll play it because it's us."
The vox article also mentions what I said in my answer about getting more songs in a given period of time on radio to attract a larger audience. From the article: "Top 40 station that offers "twice the music," which really means it cuts hit songs in half to make them shorter."