The word "Nada" literally means:
Na = Nothing,
Da = Giver/Supreme Power
So, Nada is a connection between humans and god, when a human reaches Shoonya (nothing or zero) being far from the material world. Nada Meditation is practice with sounds to reach the god or to do self-realization.
When a human tries to create nothingness at the body level by the conscious mind, but still some parts of the body are active because of the sub-conscious mind, in this particular way of practice, the body goes for a recondite relaxation (but not the same as sleeping), being still as sitting in a posture, focusing on the sound or vibrations and getting the inner peace is the practice of Nada Meditation.
Nada Meditation is called the connection between humans and supreme power because when the body is tranquil, you are able to listen to the sound which has no breaking points or which is the same in frequency always, known as the sacred sound of the universe "OM".
The word "Ahata" literally means to hit or struck a material thing. The Nada Sound or Vibration produces when we hit on a material such as Sound Bowl or Gong. Every sound has a medium of sound or vibration production. Without any source, no sound can be produced. But the sound Ahata is mortal. For example, you play the Gong with more force, and it will keep making a sound until and unless the frequency is low and after that, it finishes.
All sounds produced by Ahata are artificial which can be controlled by us. Ahata sounds are beautiful or noisy depends on the medium and the producer. The Meditation on Ahata Nada is recommended but the best suggestion is using Vedic Sound Instruments because the sound is much clear and beautiful in Vedic instruments such as the flute.
The word "Anahata" literally means the sound which can not be produced by hitting the material together. Anahata refers to the universal sound which is automatically produced in the universe with the same tempo/speed, same vibration, and same frequency. The universe is really extensive or huge. It is limitless and what we know about it is only an observable part of the universe. If you meditate in any corner of the universe, and distract yourself with the mortal sound and try to listen to the universal sound, you will feel so connecting to God and go for self-realization.
The sound produced in Anahata is natural, universal, automatic, and remains the same in all situations. It can not be controlled by anyone or divert.
When a practitioner does Meditation with Ahata or Anahata, called Nada Meditation. In this Meditation, a yogi concentrate his mind on the sound or vibration. Nada is a sound without any meaning or words/phrases etc., that's why there is no meaning of Nada Sound. Nada Meditation is practiced by thousands of people because this is not about any religion and does not promote any special area or people.
When some words come into any sound frequently, it may promote any type of culture, area, people, etc. Nada is optimal Meditation because it is not about any kind of promotion. It heals you like the sea waves do, as the singing bowl does, temple rings do, waterfalls do, flutes do, and many others.
1) Ancient musical instrument such as the Flute
2) Meditate on Sitar
3) Meditate on Tabla and Sarang
4) Instrumental Music of Gayatri Mantra (only music)
5) Meditate on natural sounds such as river water
1) Meditate on Soul
2) Meditate on the sound of breath
3) Meditate on the sound of the brain
4) Meditate of vibration of the body
5) Meditate on the heartbeat
1) Energy conservation
2) Increase the level of concentration
6) Increase dedication
7) Increase consistency
9) Healthy Heart
10) Healthy Brain
11) Increase memory power
12) Reduce Stress
13) Fix the mood
14) Fix the blood pressure issues
15) Decrease anger