I love all that Pink Floyd's album, when I was 19 I knew it by heart all of it from the very beginig to the end.
One English translation for this is "Hey you!" Can this be used to get someone's attention, or is it only to be used as an affectionate greeting?
The sound says something different to me. The norwegian "Du" as I learned so far, should sound more like a longer german "ü" or french "u". Not like the english "de". Or am I wrong in that case?
In its pure u-form the Norwegian u sounds like in English true or good (keep the vowel long to hear it better).
That said, when spoken rapidly u in du can sound quite differently to its pure form, and quite similar to the computer voice in this case.
Just be careful if you use the rapid-speech-form of u. You might end up saying other vowels instead. And if not obvious from the context it would be a quite different word. For example a few I can think of from the top of my head:
du (you) vs. dø (die) vs. det (this/that)
hurra (hooray) vs. hora (the hooker/the prostitute)
mur ((brick) wall) vs. mor (mother) vs. mør (tender; stiff) vs. mer (more)
and so on...
with hurra and hora, wouldn't they sound different because the stress on hurra would be on the a, and in hora the stress would be on the o. right?
Because it is correct. It can either be "Hey, you" or "Hi, you". It's mostly used as "Hey, you" but both have the same meaning. It is used to get someone's attention.