Nāda Yoga (नादयोग) is an ancient Indian metaphysical system. It is equally a philosophical system, a medicine, and a form of yoga.
The system's theoretical and practical aspects are based on the premise that the entire cosmos and all that exists in the cosmos, including human beings, consists of sound vibrations, called Nada. This concept holds that it is the sound energy in motion rather than of matter and particles which form the building blocks of the cosmos.
Nāda yoga is also a reverential way to approach and respond to sound. In this context, sound [and] music carry a spiritual weight more meaningful, respectively, than what sensory properties normally provide. Sound and music are considered to play a potential medium/intermediary role to achieve a deeper unity with both the outer and inner cosmos.
Nāda yoga's use of sound vibrations and resonances are also used to pursue palliative effects on various problematic psychological and spiritual conditions. It is also employed to raise the level of awareness of the postulated energy centers called chakras.
Music has been used by most Indian saints, prophets as an important and powerful tool in the quest for the achievement of Nirvana; notable names to be mentioned here include Kanakadasa, Thyagaraja, Kabir, Meerabai, Namdeo, Purandaradasa and Tukaram.
The Nāda yoga system divides music into two categories: internal music, anahata, and external music, ahata.
While the external music is conveyed to consciousness via sensory organs in the form of the ears, in which mechanical energy is converted to electrochemical energy and then transformed in the brain to sensations of sound, it is the anahata chakra, which is considered responsible for the reception of the internal music, but not in the way of a normal sensory organ.
The anahata concept refers to one's own personal sound vibrations, which are thought to be so closely associated with one's self and the Self that a person can not share their anahata with another human being. In other words, this inner sound is sacred and once reached will open the practitioner's chakras, which ultimately will unite the body to the divine/cosmos.
With continued sounds, a focused mind and controlled breath, the individual can, according to Nāda yoga, "listen in on" their own anahata, their own "inner sound", which can take up to nine different forms. Such a process of inner awareness and sensitivity leads to increased self-recollectedness and finally to awakening.
To concentrate on this inner sound as a support for meditation is very helpful to tame the mind, and when it has been clearly recognized, used for self-recollectedness in outer life as well. Eventually, it can be experienced as penetrating all matter and indeed vibrates eternally throughout the Creation.
In Nāda yoga, one of the main breathing sounds is ahaṃ, where each part of the word (a ha ṃ) is focused on and spoken individually. The echoes produced by each of these spoken letters is a time where the yogi should immerse himself and rest. Now, because of imbalances within the human body, Nāda yoga begins by removing the ailments and impurities by "awakening the fire in the body (jāṭhara)" with the use of a sound resembling that of a bee. It is important to note that when the yogin is forming sounds, his/her mind should not wander off to other entities.
The ŚūraṅgamaSūtra, often spelled Shurangama Sutra or Surangama Sutra in English, is a Mahayana sutra and one of the main texts used in the Chán School in Chinese Buddhism. In the Surangama Sutra, Avalokitesvara says that he attained enlightenment through concentration on the subtle inner sound. The Buddha then praises Avalokitesvara and says that this is the supreme way to go.
"How sweetly mysterious is the Transcendental Sound of Avalokiteshvara! It is the pure Brahman Sound. It is the subdued murmur of the seatide setting inward. Its mysterious Sound brings liberation and peace to all sentient beings who in their distress are calling for aid; it brings a sense of permanency to those who are truly seeking the attainment of Nirvana's Peace..."
"All the Brothers in this Great Assembly, and you too, Ananda, should reverse your outward perception of hearing and listen inwardly for the perfectly unified and intrinsic sound of your own Mind-Essence, for as soon as you have attained perfect accommodation, you will have attained to Supreme Enlightenment."