Hörbuch = /ˈhøːɐ̯ˌbuːχ/
Hörbücher = /ˈhøːɐ̯ˌbyːçɐ/
Thanks for the IPA script. I prefer it over trying to use english sounds to describe it.
This is the first time I have to pronounce something with both the ö and the ü and I must say that was pretty difficult.
I got it wrong, too. "Das Hörbuch" is the singular form, I guess in plural becomes "(die) Hörbucher"