It is the fundamental sound in the existence.
In the yogic culture, the entire existence is seen as a complex amalgamation of sounds. The three root sounds that come out of this are “Aa”, “Oo” and “Mm”. Uttered together, these form “Aum”.
“Aum” chanting activates and energises various sections in the body, reverberating through the entire system. Furthermore, daily utterance of this sound can bring peace and balance and is known to relieve the practitioner from numerous physical and mental ailments with regular practice.
▵ Mantras Explained – Benefits of Chanting Mantras and the Science Behind It
Fundamentally, there are three sounds in the existence. Any given sound can be created out of these three sounds. If you know something about a color television, there are only three color webs. Given these three color webs, any number of colors can be created. Similarly, given these three sounds, any number of sounds can be created. You can see this with a simple experiment: without the use of the tongue, there are only three sounds you can utter: “aaa”, “ouuu”, and “mmm”. Even if you cut off your tongue, you can still utter these three sounds. For any other sound, you need the use of the tongue. You are using the tongue only to mix these three sounds in many ways to produce all the other sounds. There are so many millions of sounds you can create with your mouth, but a person who is mute can only say “aaa”, “ouuu”, and “mmm”. He cannot say anything else because he is not able to use his tongue.
▵ AUM – The Fundamental Sound
If you utter these three sounds together, what do you get? AUM. AUM is not some religion’s trademark. It is the fundamental sound in the existence. It is said that Shiva can create a whole new existence just by uttering three AUMs. This is not a fact, but it is a truth. What is the difference between a fact and a truth? Let us say you are a woman. Does that mean your father made no contribution towards you? Does that mean your father does not exist within you? No. So the fact is, you are either a man or a woman. The truth is you are both. It is not that Shiva is sitting somewhere and uttering AUMs. That is not the point. What is being said is that everything is just a vibration.
Excerpt – Mantras Explained – Benefits of Chanting Mantras and the Science Behind It (Isha)