Using a mantra and the chanting of sacred sounds is a central part of yogic meditation. The word mantra comes from two syllables: "man," meaning mind, and "tra," meaning tool. Using a mantra is a tool that cultivates reflection, awareness, and concentration.
So Hum is referred to as the "Mahamantra," the Greatest Mantra, and is considered one of the most powerful meditation techniques. In Sanskrit, the most ancient of languages, the inhalation's sound is termed "So," and the exhalation is "Hum." Combined, the sound So-hum is translated as "I Am That" or "So Am I."
When using this mantra, the sounds are used silently.
When you first start using this mantra, the first thing you will notice is the inhalation. The exhalation has different sounds, different forces, and even the air has different temperatures. On the inhalations, the prana (cool) is brought in. On the exhalation, toxins (carbon dioxide) are expelled, which feel warmer. During this meditation, gradually, both the breath and the sound will become quieter and quieter and quieter, and the breath becomes so soft that it almost seems to stop. By quieting your breath, you quiet your mind.
Then, when your mind becomes quiet, you transcend thought. The mantra "So-Hum" entirely disappears, and your breath will pause momentarily. Time itself comes to a stop. You are aware but not of any one thing. You're in the field of pure consciousness, the realm of the spirit.
Here is how to do it;
Find a comfortable seated position.
Place your hands on your thighs and gently close your eyes.
Keep the chest lifted, relax your shoulders, jaw, and scalp.
Draw your chin in slightly and let the back of your neck lengthen.
Relax your abdomen and breathe through your nose.
Now, bring your attention to the rhythm of your breath, observe the inhalations and exhalations.
On your inhalation, listen for the sound of "So."
And as you exhale, listen for the sound of "Hum."
Keep your focus on your breath while silently repeating, "So-Hum."
There is no need to force if the mind wanders, gently return to the sounds.