To the Sufis, singing is prana, the breath of life itself, the most potent of all the musical healing modalities. According to Hazrat Inayat Khan, the ancient singers would chant a single note half an hour at a time in order to investigate the effects of that note on their various energy chakras: "what life current it produced, how it opened the intuitive faculties, how it created enthusiasm, how it gave added energy, how it soothed, and how it healed. For them it was not a theory, it was an experience."
— Mitchell L. Gaynor, Sounds of Healing