With deep-sea diver sounds
"Deep-sea diver" has a rugged masculine connotation in sharp contrast to speaking in a Donald Duck voice.

It is interesting that the sounds produced by gasps, burps, and flatulence are about the same as in air. The perception of sound by divers in Helium environments is also unchanged. I always found it interesting that vibrating of the vocal cords was effected so much more than ear drums.