AUM expresses the Divine Immanence.
It is associated with meditation and yogic practice.
The sound AUM permeates peace and serenity.
A-U-M is human's song of aspiration for the Lord.
All of manifestation is created, preserved in the created state for some time, then eventually destroyed. AUM, therefore, encompasses the three vibratory energies required to create, preserve, and destroy, and each of these energies vibrates at a different frequency.
The three letters of AUM represent these three vibrations inherent in creation. (Even though the variant spelling in English is “Om,” AUM is more accurate.) “A (Akaar)” represents the vibration that brings into manifestation the created universe; “U (Ukaar)” represents the vibration that preserves the creation; and “M (Makaar)” represents the destructive vibration that dissolves the manifested universe back into the Infinite Spirit.
Traditionally in India, Aum is chanted three times. One reason is to invoke the blessings to the three universes (or the three “bodies” the soul is encased in) — physical, astral, causal. Another is a reminder of these three aspects of Aum.
When chanting AUM, the three letters (sounds in Sanskrit) should be pronounced properly for true mantric power:
The “A” in AUM represents the cosmic creative vibration, and should be pronounced short, as in the first “a” in “afar,” rather than long as in “arm.” When this sound is heard in meditation, it has the highest pitch of the three.
“U” (pronounced “oo” as in “moon”) is the cosmic vibration of preservation. It maintains all creation in a state of equilibrium. This sound, when heard in meditation, is pitched somewhat lower than the first.
“M” represents the vibration of cosmic dissolution, which draws all creation back into the Absolute at the end of a universal cycle. The time allotted to cosmic manifestation is known as a Day of Brahma, and spans a period of billions of years. This vibration of the AUM sound, when heard in meditation, is pitched lowest of all, like a deep rumbling.
In addition, these three frequencies should be chanted at different notes:
The notes of the first “AUM” are higher, and should be sung loudly. The second note-sequence is a little lower, and is sung more softly. The third sequence is lowest, and is the softest of the three.
A final point: When chanting AUM, the “M” should be given equal emphasis to the preceding two vowels.