Can anyone explain to me how a singer/artist squeeze in more than 4 syllables between subdivisions? i know it has something to do with tempo, but how do you count the beats between subdivisions to make sure you're not using more notes than what the meter suggest? does that mean the artist is using smaller notes to expand the subdivision when they use more than 4 syllables??
Yes, they have to! Generally speaking, music is divided into bars, all of which are the same length or duration. So, as a simple example, in a piece in 4/4, a singer could sing 'ven-om-ous-snake' using 4 crotchets. If the words contained 5 syllables, one crotchet could be split into two quavers, so 'hip-po-pot-a-mus' could be c-c-q-q-c.
More syllables means more notes which means shorter notes, but in this example, the maximum beats needs to be 4. In fact, that's the minimum too - each bar must contain those 4 beats. So singing 'kill-er-bee' would need maybe c-c-m. (Minim (m) is 2 beats long.)
does that mean the artist is using smaller notes to expand the subdivision when they use more than 4 syllables?
Yes. Basically you can subdivide with any number of notes. When the meter is simple the "default" subdivisions are by 2. A beat is divided into 2 subdivisions which each can be divided by 2 again for 4 subdivisions of the one beat. If you want divisions by other than 2, you create tuplets where you just stick in however many notes you want and then put the number of subdivisions over the group. The tuplet subdivisions should be played with an even amount of time per each subdivision. Below shows rhythms with one beat follow by increasing subdivisions...
Notice the beats that are subdivided into 5 notes. You can use a combination of subdivisions at various levels and tuplets. This brings up an interesting performance issue. It's each to play subdivisions by 2. Subdivision by 3 is pretty natural. But subdivision by odd/prime numbers is tricky. The 5 tuplet probably would be faked by many (at least me) but playing 5 as 2 16ths and a tuplet of 3 isn't too tough with practice.
Past number 4 any number can be the sum of 2's and 3's.