Answer :
the word for 4 people playing musical instruments is called a "Quartet'. I hope this helps!
2 = duo or duet
3 = trio
4 = quartet ***
5 = quintet
6 = sextet
7 = septet
8 = octet
3 = trio
4 = quartet ***
5 = quintet
6 = sextet
7 = septet
8 = octet