Sri Chinmoy: Here you have to know that this sound you hear is the sound of the inner Divinity, and inside this Divinity, all the time, Infinity is growing. The first sound is the Source, the cosmic sound. Inside that is the infinite manifestation of sound. The first sound is the cosmic vibration, Anahata we call it, the soundless sound. Then inside this sound, you will hear an infinite number of sounds because from the Divine One, many have come.
God was One. He wanted to divinely divide Himself up and thus enjoy Himself in multiple forms. That is why we are now here on earth.
Now, this soundless sound that you hear within contains within itself the creation. That is why there are other sounds that you hear inside it. Those inner sounds are vibrating and offering you the manifestation inside your consciousness. The multiple sounds are the sounds of identification with the universe, with the manifestation. The first sound is the Source of realisation, the Highest. The other ones are the sounds of the infinite manifestation.