OM is a universal, sacred symbol. It is considered to be the primal sound of the universe. According to tradition, ancient sages were able to hear the subtle vibrations produced by everything in the universe, and they identified OM as the most elemental sound of creation. In the beginning there was sound, from that sound everything came into existence.
In a quiet environment, you can hear the vibration of OM in the crashing of ocean waves, in the stillness of a forest, or in the rush of the wind.
OM is often used by meditators as a mantra to assist in reaching higher states of awareness. Many mantras and prayers begin and end with the sound OM.
When you chant this sacred sound you connect your body with spirit.
Through chanting the sacred sound of OM you begin to experience the oneness with the universe and everything in it. Chanting the OM mantra helps us to experience our true nature as a vast open light or energy. Chanting OM can have a very healing effect as it puts us into the present moment. Listen and chant along here.
Sogyal Rinpoche, a Tibetan Buddhist teacher, tells us
“ A meditation technique used a great deal in Tibetan Buddhism is uniting the mind with the sound of a mantra. The definition of mantra is “that which protects the mind.” That which protects the mind from negativity, or which protects you from your own mind, is mantra.
When you are nervous, disoriented, or emotionally fragile, inspired chanting or reciting of a mantra can change the state of your mind completely, by transforming its energy and atmosphere. How is this possible? Mantra is the essence of sound, the embodiment of the truth in the form of sound. Each syllable is impregnated with spiritual power and condenses into a deep spiritual truth.”
Sounding OM is one of the easiest mantras to chant and can be done anywhere, anytime. In just a few minutes you can change your whole vibration just by chanting OM.
It can be helpful to visualize the OM symbol as you chant and connect in with your breath. Allow the vibration of the sound to travel through your body as it penetrates deep into your cells. 
Sometimes while meditating I wear a necklace with the OM symbol, I find it helpful to hold
the OM pendant while chanting. It gives me a tactile sensation and connection to the sound. If you would like to see some of my OM jewelry, please visit my web site.
Rest in the universal sound of OM.
Namaste,
Debra