Can people easily distinguish the difference between the sounds of |O| and |WO|, as well as |U| and |WU|?
By no means have I been able to figure them out, for all of my life. To my surprise, many native speakers I have talked to seem unable to distinguish between them, either.
Can anyone help make my life complete?
In my dialect (very close to General American, I've moved a lot) the following pairs are very distinct:
I would never confuse these in normal conversation, even if I wasn't paying much attention. If the area was noisy I might have trouble distinguishing /i/ from /ji/, but the same could be said for many sounds (/p/ and /b/ or /ɛ/ and /ə/) which are also considered to be distinct.
As a native American English speaker, I can definitely hear the difference between /o/~/wo/, /u/~/wu/, etc. I think most native English speakers can.
As for learning to distinguish them better, looking at the speaker's mouth while they talk may help. The lips are closer together and more rounded for /w/ than for /o/ and /u/, so when a person pronounces /wo/ and /wu/ you should see their lips begin close together and very rounded, then separate somewhat. Paying attention to the visual difference could help you pick up on the auditory difference. (This should also be easier to do with /wo/ than /wu/, since /w/ is more acoustically similar to /u/ than to /o/).
I think it depends strongly on whether someone is enunciating properly or not. In everyday speech many people don't, which can cause certain sounds to "bleed together". I believe this is called elision and is the natural result of making a certain combination of words easier to pronounce. One example of this is the already mentioned "three years" and "three ears".
