Bhashya
तथा श्रोत्रं दिशोऽभवन् ; दिशः प्राच्यादिविभागेनाव-स्थिताः ॥
In plain words
Thus the ear became the quarters of space, and those directions remain established through divisions like the eastern.
Close to the Sanskrit
Thus the ear became the directions; the directions are situated by the division beginning with the eastern.