what difference beat value makes in time signature [duplicate]

Question

I am trying to understand the intuition behind the time signature. My confusion is as below :

1. My first confusion was why in general every metronome beat is considered a quarter beat, but what I realized as I read more, is that usually it's a standard but it's not necessary. I mean it's usually mentioned, (for example) that the tempo is 60 bpm and each beat is a quarter/whole/half beat. Please correct me if I'm wrong here.

2. Now coming to time signature, Let's say my music is in 4/4 and is 60bpm. That means every beat is a quarter note. From this I understand that my music is going to feel like it's structured in 4 beats or pulses at a time. The pulse is going to feel like 1-2-3-4, 1 having more accent.

3. Now lets say my music is in 4/2 and is 60bpm. I am unable to understand what difference this change in beat value will bring in my rhythmic feel, because All I can think of, is that if I put that in a metronome, every tick is a half beat now; then there is no difference between what I was playing previously, (for example, 4/4 in point 2), and if I say that the metronome beat is still a quarter beat, then its just going to make my music sound slower.

Please help me in clearing this confusion. Thanks. :)

Answer 1

Changing your time signature will change your tempo. Having a time signature of 4/4 at 120 BPM for 20 bars will give you a song 20 seconds long.

Having a time signature of 3/4 at 120 BPM for 20 bars will give you a song 15 seconds long.

Having a time signature of 2/4 at 120 BPM for 20 bars will give you a song 10 seconds long.

If there are less beats in a bar, (or measure) your bars (or measures) will go by much faster, because you must complete 120 beats in a minute.

If you want a song with a length of 1 minute that has a tempo of 120 and a time signature of 4/4, it will take 30 measures.

If you want a song with a length of 1 minute that has a tempo of 120 and a time signature of 3/4, it will take 40 measures.

Time signature is important to many things, especially the repetition of a certain measure(s). If I were making a song in 4/4 but all my rhythms restarted at the 3rd beat, (equivalent to 3/4)then it would be very hard to count the measures because having the song divided into measures would then be useless and unhelpful. having a time signature of 3/4 allows me to use quarter notes and 8th notes and still achieve my 3-note rhythm due to the time signature. A correct time signature will make dividing the song into measures useful again.

Another important reason behind time signatures, is the measure indication of a metronome. If you were playing a 3-note rhythm in 4/4, your metronome will indicate the start of the next measure at the wrong time. having a 3-note rhythm and a metronome set to 3/4 will make your metronome indicate the start of the next measure at the correct time.