Posture: Sit straight in Easy Pose, (Cross legged or in a chair with feet flat on the floor knees as wide as the hips.)
Eyes: Meditate at the Brow Point.
Mantra: Produce the five primal sounds (panj shabd): S, T, N, M, A, in the original word form:
SAA: Infinity, cosmos, beginning
TAA: Life, existence
NAA: Death, change, transformation
MAA: Rebirth
Each repetition of the entire mantra takes 3 to 4 seconds. This is the cycle of Creation. From the Infinite comes life and individual existence. From life comes death or change. From death comes the rebirth of consciousnes to the joy of the Infinite through which compassion leads back to life.

Mudra: This mantra can be done in many different mudras. Most common is to begin in Gyan Mudra. The elbows are straight while chanting, and the mudra changes as each fingertip touches in turn the pad of the thumb with firm pressure.
On SAA, touch the first (Jupiter) finger
On TAA, touch the second (Saturn) finger
On NAA, touch the third (Sun) finger
On MAA, touch the fourth (Mercury) finger
Chant in three languages of consciousness: Human: normal or loud voice (the world), Lovers: strong whisper (longing to belong),
Divine: mentally; silent (Infinity)

Note: Meditate on the primal sounds in the “L” form. This means feel there is a constant inflow of cosmic energy into the solar center, or Tenth Gate. Imagine the energy of each sound moving through the Crown Chakra, and down and out through the Third Eye Point as it is projected to Infinity. This energy flow follows the energy pathway called the Golden Cord—the connection between the pineal and pituitary glands. Some people may experience headaches from practicing Kirtan Kriya. The most common reason for this is improper circulation of prana in the solar centers. To avoid or correct this problem, You may also want to try covering the head with a natural fiber cloth.

Time: Begin the kriya in a normal voice for 5 minutes; then whisper for 5 minutes; then go deep into the sound, vibrating silently for 10 minutes. Then come back to a whisper for 5 minutes, then aloud for 5 minutes. The duration of the meditation may vary, as long as the proportion of loud, whisper, silent, whisper, loud is maintained. For example, seniors are recommended to practice Kirtan Kriya for 12 minutes (2 minutes each cycle) to slow memory loss. click here

To End: This sequence will take 30 minutes. Follow with one 1 minute of stretching the arms over your head and spreading the fingers wide, shaking them out, circulating the energy, inhaling and exhaling 3 times. Relax.

Comments: 
Each time the mudra is closed by joining the thumb with a finger, the ego “seals” the effect of that mudra in the consciousness. The effects are as follows:
1st finger: Gyan Mudra Knowledge
2nd finger: Shuni Mudra Wisdom, intelligence, patience 3rd finger: Surya Mudra Vitality, energy of life
4th finger: Buddhi Mudra Ability to communicate
This meditation brings a total mental balance to the individual psyche. Vibrating on each fingertip alternates the electrical polarities. The index and ring fingers are electrically negative, relative to the other fingers. This causes a balance in the electromagnetic projection of the aura.

Practicing this meditation is both a science and an art. It is an art in the way it molds consciousness and in the refinement of sensation and insight it produces. It is a science in the tested certainty of the results each technique produces. Meditations have coded actions to their reactions in the psyche. But because Kirtan Kriya is effective and exact, it can also lead to problems if not done properly. Yogi Bhajan said at Winter Solstice 1972 that a person who wears pure white and meditates on this sound current for 2-1/2 hours a day for one year, will know the unknowable, and see the unseeable. Through this constant practice, the mind awakens to the infinite capacity of the soul for sacrifice, service, and creation.

Checkpoints For Kirtan Kriya:
If during the silent part of the meditation, the mind wanders uncontrollably, go back to a whisper, to a loud voice, to a whisper, and back into silence. Do this as often as you need to.

Home page for The Alzheimer’s Research & Prevention Foundation

An excellent article in Huffington Post by Dr. Dharma Singh Khalsa about the benefits of Kirtan Kriya

Source: Spirit Rising Yoga