These stages are termed as para, pashyanti, madhyama and vaikhari. Each level of sound corresponds to a level of existence, and one's experience of sound depends upon the refinement of one's consciousness. It takes a realized consciousness to experience the full range of sound, the full range of existence. The seers who can comprehend the four stages of sound are known as Manishis. These four levels of sound correspond to four states of consciousness.
Para represents the transcendental consciousness.
Pashyanti represents the intellectual consciousness. Madhyama represents the mental consciousness. And Vaikhari represents the physical consciousness. These states of consciousness correspond with the four states known technically as jagrat, svapna, sushupti, and turiya - or the wakeful state, the dreaming state, the dreamless state, and the transcendental state. Shabda-brahman in its absolute nature is called para.