The vibration in each nadi creates certain feelings or urges in the consciousness. Sensual desire is aroused by some, sloth by some and sorrow by some others. To reverse this, when there is sensual desire there is a vibration in some nadis, and when there is anger there is vibration in some other nadis, and so on for each type of feeling or emotion or urge. We know this from actual experience. When we are at ease there is a special glow on our face and this glow is caused by some nadis being cool and unagitated. There is a saying "One's inner beauty is reflected outwardly on one's face". Our emotions cause their own reactions in our nadis. If we succeed in bringing the nadis under control we shall be masters of our urges and feelings. There will then be no need to depend on any external agency for the purpose.
One way of acquiring control over the nadis is the practice of Rajayoga of which pranayama is the most important feature. Mantra Yoga is another. When we vocalize a syllable, the vital breath is discharged through the space intervening our throat, tongue, lips, the upper and lower parts of the mouth, etc. It is then that the syllable is voiced or the "aksara dhvani" produced. Vibrations are created in the nadis located in those parts of the body where the vital breath courses through as a consequence of the aksara-dhvani.