If you haven't read about it already, there is no audible dialog in the movie. There is sound, you hear actors breathing, you hear them when they are in pain or pleasure. But other than that, this is almost like a silent movie. Does it work? You bet it does! It's not about losing ones voice though (it never is something that is touched upon during the movie, it just happens), it is about much more.
The fact that it is obsessed with pleasure, is just a metaphor. A metaphor for what people are looking for in life. It is not about repeating one self (although at times it might seem that way), but to further go down that rabbit hole. Kim Ki Duk is known to make strange movies. Now he has gone to the experimental stage ... rejoice or run for cover