[steven]

I think this goes for all "vowel" sounds in Japanese, but I've noticed it particularly for the う sounds... English speakers have a tendency to drag out the vowel sound too much. If anything, the う sounds should be almost inaudible. So if you are having trouble hearing it, then maybe that means you've found a good source for your listening!

For example です has a す at the end, but many people don't even bother saying the う portion of the す and it ends up being like でS, if you get what I mean. (although I get the feeling that following through with the す sounds more polite).

おはようございます is another example (of a couple of things I've been talking about, actually). To be more specific, the す at the end can be said as an "s" sound. Some people drag that "s" out quite a bit. Another feature of it is that most people don't say the whole phrase. Think of it as English speakers saying "G'mornin'!" or "'mornin'" or something like that. I've even heard Japanese people jokingly say "はざす" very clearly instead of おはようございます. A lot of people say おす, as well. It's not really polite, but it can be used at pretty much all times of the day.

But yea, your ears are you friend. Learn to trust them. Go by what you hear more than by what you see. By that I mean, don't say a word the way it is written, say it the way you hear it. If you have the means, record yourself and listen to the playback! You might be dissapointed with the resutls, but it's a good way to practice (as it's also a good way to practice singing or playing an instrument).

Disclaimer:
I know I said learn to use your ears instead of your eyes... but that is in regards to going from written to spoken language. Using your eyes is EXTREMELY important with Japanese. I'll give you a few examples of using your eyes. One example would be to watch peoples' mouths. This is a part of listening. You can learn to kind of lip read (although I think it's a lot harder in Japanese than in English). You can also study peoples' mouths to see how they "shape" their words. You can check your own "shapes" with a mirror in the privacy of your home later on. Another thing about "speaking" Japanese is that gestures and mannerisms and when and where to say things is very important. So watching people and what they do is a very important aspect of the language. This is not an option for a lot of learners of Japanese though.

In the end though, you can't think of this stuff ALL THE TIME, so you should just review this kind of stuff every now and then to keep it in the back of your mind. If you worry too much about every little thing, you'll never get a word out... and that's the most important part!