If you can ascertain the stark truth, void of its intricacies, you will find that the sound and its echo are in reality one and the same thing. (You feel as if you hear two distinct voices, but the echo has no substance, and the originator of both is the same agency.)
Note: What is the echo? It is repetition of sound by reflexion of sound waves. The sound is a reality. It has existence. But the echo is artificial, It has no existence. The poet possibly means that the real actor is Allah, and the man does not count.
آں نداکش اصل بر بانگ نداست
خود ندا آنست و ایں باقی صداست۔
(Roomi)
He who raises the sound is really responsible for what is heard. He is the sound and the other is a mere echo.
Before the veil was lifted from me, I used to feel that I remembered You and thanked You. But when the light dawned on me, I realized that You alone were the adorer, the adoree and the adoration, all together (lbn e Arabi)

The Echo and the call are the same,
If only you could know the secret of it,
They both were one, but two became only when hearing came.

The Echo and the call are same,
if you sound's secret knew,
They both were one,
But two became only when "hearing" came.

Echo and sound are one and the same,
Language's twist and turn understand,
Both were one, hearing has much difference made.

Echo is in fact the sound,
You ponder and will discern that
They were one but in listening became two.