Speech is Rik, and therefore when a man utters a Rik verse he neither breathes up nor down. Rik is Sâman, and therefore when a man utters a Sâman verse he neither breathes up nor down. Sâman is udgîtha, and therefore when a man sings (the udgîtha, Om) he neither breathes up nor down.

In plain words: Speech becomes a verse of the Rig Veda, the verse becomes a sacred chant, and the chant becomes Om. So when a person recites a verse, sings a chant, or sings Om, he does it while holding the breath.