While sound can't travel directly through the vacuum of space,there is noise in the universe. OM is the eternal sound. It is the sound which is there in the universe all the time.
It is the seed of the whole creation; is the sound of creation. There they don’t say which word; the word is OM.
This single syllable comes from the Vedas. As a Sanskrit word, it means avati raksati - that which protects you, blesses you. The word is the contraction of the word SOHAM, which means the vital breath, the sound of life. He balances the Self by giving it all its power by establishing harmony between the various vehicles of the integral man in his three fundamental divisions (body, mind and spirit).
OM means many things and is in many religions in some or the other form as for exemple truth, eternity, purity, infinity, love, peace, Divinity.
Science tells us that the Universe began with a big bang and the sound of the big bang is actually a big OM, which didn’t just happen once; it is ongoing.
As the initial vibration of OM emerges from the unmanifest, it diversifies into all the different vibrations of the Universe, which manifest as the world we know. It therefore contains within it all the mantras, sounds, and vibrations of the Universe. OM is the collective sound of the Universe, the Primordial Sound.