Sirena, I was just thinking the same thing. I hear many people say "pardon me?" all the time. I never knew whether they missed the entire sentence or just a few select words (from lack of attention, background noise, whatever reason.) Anyway, I asked my OTHER roommate who just came home from work tonight about the whole "milk" and "beer" thing. The difference is that he is deaf. I didn't give him any background information regarding this thread; I turned off my voice, and had him lipread both words. He had no prior knowledge, no sound, no speech discrimination. He got both instantly. The only reason I mention this is in reference to jazzy's post -- in that she misunderstood when she tried this -- it is indeed subjective for everyone. My point was that it CAN BE possible for us deaf people to differentiate between the words.
Now, as far as using the prior knowledge variable in Jillio's post -- it is really no different than anyone putting on a blindfold for 5 minutes and asking them to feel the difference between an apple and an orange. It may take a second of feeling the two objects to comprehend the difference, but the difference is there, prior knowledge or not. I cannot possibly understand what it is like to be blind -- since I am not, but I should be able to detect a difference immediately between those two objects. This is what I'm trying to explain here -- that prior knowledge or not, the difference between certain words is still there, whether every deaf person can lipread it or not. It just should not be said that there is NO difference between "milk" and "beer" when clearly many of us have disputed it.
Geez .. I have already posted one too many on this subject, I owe another beer already -- I'm done! Cheers!