Om - the sound of origin; "all"
To say it right, do these two things:
1) Pronounce three syllables that run into each other: "ah" "oh" "mm."
If repeating the sound of om over and over, each "mm" runs into an "ah", resulting in a transition syllable "mah." Blend the syllables fluidly for maximum continuous resonance in the chest, throat and nasal cavities.
2) Inhale to fill the lungs, then initiate the production of the "ah" ("mah" when sung continuously) by contracting the diaphragm, as if gently forcing the air and syllable up from the abdomen through the windpipe into the mouth. Roll the "ah" up your body from base to head, essentially.
To type the symbol, choose wingdings font and type a backslash ( \ ).