erinja:

"Bush" has the IPA vowel ʊ
Esperanto usually uses the IPA vowel u

Hmmm I guess it depends on what kind of English accent you have.

I am a native English speaker yet I say "bush" just like the standard Esperanto sound (which seems a bit shorter than the American 'u' in 'whoosh'?)

But then again I live in Melbourne and have a Dutch father and a South African/Sweedish/English mother.

I think we have to be careful when describing an "English" accent, as there is a wide variation. E.g. Scottish English vs. Indian English.