Avatarika
अथाध्यात्म य एवाय मुख्यः प्राणस्त मुद्गीथमुपासीतोमिति ह्येष स्वरन्नेति ॥
In plain words
Now comes the meditation concerning the inner self: this very principal vital breath is the udgītha; one should meditate upon it as oṃ, for this breath moves onward uttering the sacred sound.
Close to the Sanskrit
Now regarding the individual self: who is this very principal vital breath, that one should meditate upon as the udgītha; because sounding with oṃ this one moves.