In one of his lectures, Alan Watts points out the value of the word Om.

I used to think chanting was silly, and things like the singing bowl has been categorized as “props” for meditation. But props can be useful. Props are what connect practice to reality, in some ways.

The value of Om, as Watts puts it, is that it uses all of the different parts of your mouth to make it, from the back of your throat (Auuuu) to your lips (mmm). And when you hold on the last phoneme of the word, the “mmm” of Om, your nose and sinuses start to shake. And it’s the most wonderful feeling in the world, just to let the inside of your face ring like it’s singing the song of the universe.

Like the Neti pot of meditation, humming or saying Om means nothing. And that’s fine, because it doesn’t have to mean anything to sound good. Like how Brian Eno composed Music for Airports for a functional reason (to have music that could be played in an airport) rather than a semantic reason.

If everything is vibrating all the time, then Om is the square of those vibrations. Or perhaps it’s an antenna that lets us feel the movement of the planet in a manageable way.