How did the approximately four minute song become (somewhat) standard? Was it influenced by the needs of radio, or was it the other way around?

You may like these previous answers. But these are not to discourage discussion here -- further questions, data, and debate are welcome.

"When did music shift from long, drawn out symphonies to the short songs of today?" at https://www.reddit.com/r/AskHistorians/comments/33xe4y/when_did_music_shift_from_long_drawn_out/ has answers from /u/joglaser , /u/erus , and /u/thesweetestpunch . This discussed history back centuries.

Similarly, "When did hour long symphonies turn into short, three minute songs?" at https://www.reddit.com/r/AskHistorians/comments/30jhxd/when_did_hour_long_symphonies_turn_into_short/ has an answer by 3fox.

For some more recent factors concerning technology, you can see "The standard duration of a pop song is about three minutes. Was it always this way? Why weren't songs longer or shorter?", with a thread under https://www.reddit.com/r/AskHistorians/comments/3o1cu3/the_standard_duration_of_a_pop_song_is_about/cvte86u/ by thesweetestpunch. (If you go to the base of the discussion, there are several severely downvoted replies along the way; depending on your Reddit settings, these replies may cause this thread to be collapsed on you.)

Edit to make it easier to copy and paste this in the future: "When and how did ~3 minutes become the standard length of pop songs?" at https://www.reddit.com/r/AskHistorians/comments/6v1jtj/when_and_how_did_3_minutes_become_the_standard/ ; check both replies by hillsonghoods.