Well, there is this nice passage from Ovid's Fasti in which he describes the Ludii Megalensi, a festival to honor Kybele, the Great Mother.

He describes how the priests are playing the tambourine (or some sort of instrument like that) and flutes if I remember correctly.

Flutes and drum like instruments were common for festivals and although the Ludii were only accessible to Roman citizens, the lower classes probably heard some of the procession anyways.