The term for a rhythmic pattern played by the bass instruments, tuba, bass, sax, or string bass on the first and third beats of each measure is.

Two Beat

Explanation:

Two beat also commonly known as playing in two, is a form of rhythm organization wherein the bar's first and third beats are accentuated (especially by the bass), frequently leaving the second and fourth beats silent, with the consequent "boom-chick" sound.

Two-beat was particularly prevalent in early jazz but can also be found throughout all periods.