Naad Yoga is the practice of Bhakti Yoga using sound waves and resonance to reach a state of inner peace, called Anhad Naad and often practiced by the Sikh tradition.
Anhad Naad, when a sound vibrates at a true pitch in unison with a light wave during mystical devotional. The word Naad simply means sound. Union with frequency of light/sound is the goal of Naad Yoga. In Yoga there are two kinds of sounds in the Universe, Ahad sounds and Anahad sounds.
Ahad sounds are created by striking an object, like the wind blowing through the trees or the breath blowing through the vocal chords and shaped by the mouth. Ahad sound vibrations are frequencies that are heard by the ear.
Anhad sounds or Light/Sound is the energy waves in the energy of struck melody or waves which become the un-struck melody and keep penetrating deep into the heart and cosmos. Anhad sounds are closely related to the wavelength of light, which may be referred closely to a soul experience. The anhad is a felt or seen experience.