They pushed open the iron doors and found Arngeir.
Samuel handed him the Horn. "I found it."
Arngeir looked amused. "Well done, Dragonborn."
Borri, Wulfgar, and Einarth walked into the room.
All the Greybeards stood in a circle around Samuel.
"Uhhh...what are you doing?" he asked.
"Formally greeting you as Dragonborn," said Master Arngeir. "It is your final test. If you can withstand the might of our four Voices combined, you have mastered the Way of the Voice."
With that, the Greybeards all opened their mouths and sound waves passed over Samuel. The silence was deafening, yet the shouts were incredibly loud. He gasped and fell over.
He heard their voices as visions of dragons flashed in front of him.
"Lingrah krosis saraan Strundu'ul, voth nid balaan klov praan nau!" The Greybeards shouted. "Naal Thu'um, mu ofan nii nu, Dovahkiin, naal suleyk do Kaan, naal suleyk do Shor, ahrk naal suleyk do Atmorasewuth. Meyz nu Ysmir, Dovahsebrom. Dahmaan daar rok."
They stopped. The deafening silence was gone, replaced by the howling wind from outside.
He stood up, and the ringing in his ear ebbed.
"Dovahkiin. You have tasted the Voice of the Greybeards, and passed through unscathed. High Hrothgar is open to you" said Master Arngeir. "You learned a new Shout in Ustengrav, correct?"
"Yes," said Samuel. "It was called Become Ethereal."
"Could you show it to us?"
Samuel closed his eyes. "Fai!" he shouted.
The room was bathed in white light. Time seemed to slow down. Samuel looked at his arms and saw he was transparent. He was a ghost. After a few moments, the light died. He returned to normal."
"While in spirit form, you are invincible," said Arngeir. "Nothing can harm you. However, you cannot attack in this form. If you do, the spell will break."
Samuel bowed and left.