I read a lot on the web about this topic, but the answer I got mainly is "depends on how composer will write the sheet music", and it seems a convention.

What (in practical) will change? Because if that's the same, there is no need to use the "bottom" number at all (since its power of 2, and since /2, /4, /8 o /16 seems to do the same).

Really don't get why a composer will write 4/8 instead of 4/4. Any tips, suggestions and help to cover this and get some reasons?

  • And, let's face it, by the time a reader has read the 1st couple of bars, why put anything at all..? It's just being helpful!
    – Tim
    Commented Mar 22, 2023 at 9:38
  • I think music.stackexchange.com/questions/6786/… covers this ground well (although it talks about 3/x rather than 4/x). Would you agree?
    – AakashM
    Commented Mar 22, 2023 at 10:14
  • 1
    Yes, theoretically we could dispense with the bottom number, leaving just an indication that the piece has 2, 3 or whatever beats in the bar. If each bar added up to 6 8th notes a time signature of '2' would indicate 6/8, one of '3' would indicate 3/4. Or we could have '2+2+3' leaving context to confirm that the bottom figure would have (probably) been '8'. A less radical reform, and one which is already sometimes done, would be to use an actual note as the bottom figure. 2/q. and 3/q are arguably more descriptive than 6/8 and 3/4.
    – Laurence
    Commented Mar 22, 2023 at 10:16
  • Note: if 4/4 and 4/2 "sound the same but look different"... then "how it looks" is a practical difference. It can be about not crowding the page with a lot of beams, or about tricking the performer into "feeling" faster or slower. (Though more often it's about honoring some old-time conventions hailing back to "white-note" mensural notation, as mentioned in the duplicate.) Commented Mar 22, 2023 at 17:49


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