The sound of oars was certainly heard.
Clug-clank, clug-clank, clug-clank.
"Let us call together," said Merry.

"Now! As loud as you can." Both shouted with all their might.

For an instant they fancied the boat was coming toward them, and they shouted again.

But it was almost impossible to determine the direction of sound.

They could not themselves be sure of the direction of the boat.