While they are musically not spectacular at all, drones are very effective in film scoring. A drone is usually a long sustaining note or set of notes, usually in the lower register that keeps ringing without any or much musical variation through a scene. They are particularly effective in dialogue scenes where they are not intrusive but still work very well. Low drones connect to our brain in a way that we’re genetically programmed to react on low rumbling frequencies with alertnes and in extreme cases with panic as in history they most often meant life threatening things (earthquakes, volcano eruptions, thunderstorms, a horde of large animals). Therefore, entering a low drone in a dialogue will automatically give that dialogue more importance. This effect gets even more often used in thriller/horror movies where low frequency rumblings are usually part of the sound design and have been used in practically every suspense movie since the advent of subwoofers in cinemas and the revolutionary sound design in SILENCE OF THE LAMBS in 1989. As stated above, while they work effectively, they are musically rather dull and while there are many examples of composers simply holding down a note on their keyboard for 2 minutes, there are also great examples for “composed drones” that create the archaic reaction they are supposed to but still have a musical quality to them. In the end such scenes are probably a good chance to catch up on your daily output rate if you’ve spent too much time on an action sequence but if you have the time to put a little more effort into such things, there is definitely a musically more attractive way to score “drone moments” than just holding down a key.