A new song sounds before the highest consciousness, and only the raised mind can carry the tune. The number 144000 reduces to 9 when its digits are added, and 9 is the saved, higher mind, the consciousness lifted up out of 666, the flesh-count. That song is a condition of being and not a piece of information, which is why the earthbound mind cannot learn it: harmony is heard only by what has already risen. Redeemed from the earth means lifted out of ordinary earthbound thinking, since the earth here is the mind on its lower, material level. The higher mind hears what the lower mind cannot even recognize as music.
What separates the singers is not privilege but pitch of consciousness, and the tune is simply the state they have entered.
144000: the number whose digits reduce to 9, the saved higher mind, the consciousness redeemed up out of 666, the flesh-count
Throne: the highest human consciousness, the ruling seat of the mind
4 beasts: the 4 aspects of the zodiac, the 4-fold nature of a person in emotion, spirit, body, and intellect
Earth: the mind on its lower, material level, ordinary earthbound thinking