You realize we have access to the script right?
EXT. TATOOINE – ROCK CANYON – FLOOR – DAY
Artoo forces himself into the shadows of a small alcove in the rocks as the vicious Sand People walk past carrying the inert Luke Skywalker, who is dropped in a heap before the speeder. The Sand People ransack the speeder, throwing parts and supplies in all directions. Suddenly they stop. Then everything is quiet for a few moments. A great howling moan is heard echoing throughout the canyon which sends the Sand People fleeing in terror.
Artoo moves even tighter into the shadows as the slight swishing sound that frightened off the Sand People grows even closer, until a shabby old desert-rat-of-a-man appears and leans over Luke. His ancient leathery face, cracked and weathered by exotic climates is set off by dark, penetrating eyes and a scraggly white beard. Ben Kenobi squints his eyes as he scrutinizes the unconscious farm boy. Artoo makes a slight sound and Ben turns and looks right at him.
It’s not something they cooked up in post because they missed a pickup shot in Tunisia.