If it is called the origin of everything, how can Om originate from silence? Silence is absence of sound, but Om is beyond silence. All sounds come from silence, but Om is not a sound like all other sounds. Om is the very vibration of all existence, that is why it is called the sound of one hand clapping; Anahad. It is not something that happened with the clash of two hands. It is beyond space and beyond time, and is beyond words.
Om is the primordial vibration of Creation.