Om – The Sound of the Universe

Q: What does ‘Om’ mean when we chant it 3 times, what does it invoke in us?
Sri Sri Ravi Shankar:
You know, somewhere in Boston during Guru Purnima in 2010, a lady from the Boston-Connecticut area had done a research where they recorded the sound Om, put it in the computer and found that the frequency of Om is exactly the same as the frequency of earth’s rotation around its own axis. So, in some sense, earth is saying Om. It is very interesting.
Om is called the sound of one hand clapping. Om is the eternal sound; Om is the sound which is there in the universe all the time.
All the saints in the past, when they went deep into meditation, they just heard Om. So, Om means many things. It means love, eternity, purity, peace. Om is made up of several dhatus: ah-ooh-ma. Just ‘ah’ has 19 meanings.
You can derive some several thousand meanings from Om. All those meanings are attributed to Om, soOm is the seed of the whole creation; Om is the sound of creation.
In Bible too, it is said, ‘In the beginning there was a word and the word was with God and the word was God’. That is Om.
There they don’t say which word; the word is Om.
It is in all the religions in some or the other form. That is the true name, ‘Ek Omkar Sat Naam’. Om means truth. It is the name of the infinity or the Divinity. It means love. It is the origin of the universe. There is a beautiful verse in the Guru Granth Sahib, which begins with ‘Ek Omkar Sat Naam, Karta Purakh’ – FromOm everything has come, in Om everything dwells, and into Om everything will dissolve; both matter and consciousness.
The best thing is that it is a complete vibration. ‘Ah’ – affects the lower part of the body, ‘Ooh’ – affects the middle part, ‘Mm’ – affects the upper part. The total prana is represented by one syllable Om. Before birth, we were part of that sound and after death we will merge with that sound; the sound of the spirit. So, you can say many things aboutOm; there is a whole Upanishad, the Mandukya Upanishad, which is all about Om.
Now, why don’t we take only Om as a mantra? Why do we need any other mantra to chant during meditation? Before meditation, you chant Om and create the vibration, but for meditation you need different mantras. Just Om is not used;Hari Om or Om Namah Shivaya, or something else is used along with Om. 
Only recluses, those who want to do nothing with the world, or are very old are allowed to do chant Om. Those who don’t have anything to do with the world only they are allowed to do just Om. Even then, it is not advisable.