While the original source couldn't be independently confirmed, the studio behind the recently released movie, "Everest," apparently sent BBC a clip of the still unreleased film without audio effects. Instead, throughout the entire otherwise hair-raising scene, the actors speak to each other in a tone seemingly more appropriate for a focus group discussion between amateurs trying to solve a Rubik's cube than for a life-threatening situation climbing Mount Everest.
I will admit I know little about climbing, but another point I found interesting was the use of the term (or command) "on belay" and the flustered response, "On belay" in the clip. In my experience, the reply should be ordered the other way, as in, "Belay on." But perhaps either is acceptable. Hopefully, some serious mountain climbers can put that question to rest (leave a comment).
Of course, for a comparison to the final product, check out this scene in the theatrical trailer, which includes the beginning part of the scene in question (start at 1:30 to skip to the relevant portion, or start from the beginning to enjoy the full trailer):
Have you seen "Everest"? What were your thoughts on the film (with the sound effects that you heard, of course)?