Oh hang thee, I do, from the rafters above;
Though I'll often do my utmost to support thee from below.
Sometimes I'm wont to leave thee waiting in ears;
But as a rule, I'm a beast, telling thee to stop, and stop now.
What am I?
Line 2: think modern-day technology; Line 4: generic application of the word.
Line 1: another generic application of the word (by this I mean close to its definition); Line 3: for the musically-inclined.
Three-syllable word starting with S