Ancient teachings and modern science agree: all living things, all things in existence are made up at their most essential level of vibrating, pulsing energy. For millennia, mystics have recounted their experience of this energy, which is said to manifest in our hearing awareness as a humming vibration around and within everything else.
From the story of creation from the Bible "In the beginning was the word and the word was with God and the word was God" (John 1.1) both Christianity and Hinduism agree that in the beginning there was the vibration through which everything was brought into being.
The sound of OM most closely resembles this cosmic vibration that the ancients refer to. This sound is different from other sounds that humans perceive with their senses. Sounds are usually created from one object hitting another – such as 2 cymbals, drum and hand, vocal chords, waves against the shore etc. The sound of OM is not created through two objects hitting one another. It is therefore known as “Anahata Nada” “unstruck sound”. This is the sound of primal energy.
This sacred sound of OM is composed of four elements: the first three are vocal sounds: A, U, and M. The fourth sound, unheard, is the silence which begins and ends the audible sound, the silence which surrounds it.
The best explanation of OM is found within the ancient Vedic and Sanskrit traditions. We can read about AUM in the Manduka Upanishad which explains the four elements of AUM as an allegory of the four planes of consciousness.
"A" (pronounced "AH" as in "father") resonates in the throat and is regarded as the primal sound, independent of cultural contexts. The sound ”A” is produced from within the throat and is said to include, and to be included in, every other sound produced by the human vocal organs. Indeed "A" is the first letter of the Sanskrit alphabet. It represents normal waking consciousness, in which subject and object exist as separate entities. This is the level of mechanics, science, logical reason, the lower three chakras. Matter exists on a gross level, is stable and slow to change.
The open mouth of "A" moves toward the closure of "M". Between is "U", formed of the openness of "A" but shaped by the closing lips. The sound "U" (pronounced as in "who") transfers the sense of vibration to the back of the mouth. The vibration “U” represents the level of dream consciousness and lies mid-way between waking state (A) and deep sleep (M). From the sleep state of consciousness associated with “U”, object and subject become intertwined in awareness. Both are contained within us. Matter becomes subtle, more fluid, rapidly changing. This is the realm of dreams, divinities, imagination, the inner world.
AUM encompasses within itself the complete alphabet, since its utterance proceeds from the back of the mouth (A), travelling in between (U), and finally reaching the lips (M). "M" is the third element, humming with lips gently closed. This sound resonates forward in the mouth and buzzes throughout the head. This sound represents the realm of deep, dreamless sleep. There is neither observing subject nor observed object. All are one and nothing. This is the cosmic night, the interval between cycles of creation, the womb of the Divine Mother.
The last part of the sound AUM (the M) known as ma or makar, when pronounced makes the lips close. This is like locking the door to the outside world and instead reaching deep inside our own selves, in search for the Ultimate truth. When pronouncing the word AUM the first two letters "A" and "U" become combined to form the sound of “O”. The last letter "M" is still very apparent and still sounds as "M" upon pronunciation. For this reason the word AUM is shortened to OM. The word OM still contains all the characteristics of the word AUM.
The fourth sound of OM “the unstruck sound” exists within the silence at the end of the sacred syllable. It is interesting that you can’t really listen to silence, you listen to sound but how can you hear something where there is no noise?
When one really focuses on this silent sound - this unstruck vibration, one comes into the presence of stillness, presence and peace. In making the sound of OM we perceive this unstruck sound clearly in the instance after the last humming vibrations of “M” start to fade away. At that moment, that instant separating audible sound and silence. When one sits or rests in this silence there is an intensity of silence.