Often you find a misunderstanding as to what consonance means. Some imagine it as a loud sound, whereas the sound may be inaudible like the heart’s tension. For it is the heart that sings; it resounds and fills the entire organism with a special energy. The prayer itself, Aum, may also be in the heart, but it engenders the same radiations as an uttered sound.
One should become accustomed to the heart’s expression. One cannot better express his constant striving than in prayer of the heart. (Aum (opens in new tab), 32)