Reveille is a bugle call to signal the start of the military day:
Though you might see episodes of MASH where the soldiers drag themselves out of their bunks at the sound of the bugle, we didn’t do this when I was in the barracks. We just did alarm clocks, and like any soldier in the barracks, we got it as close as we could before first formation, then went outside like zombies for physical training.
But also, reveille couldn’t be heard everywhere. When I was on main post on Fort Lewis, it was easy to hear because we were pretty close to I Corps. But after we moved to North Fort, which was, at the time, old World War II barracks, I never heard Reveille or Retreat.
There are some more bugle calls on the Army website.