Not quite actually, you don't pronounce the u, it's just a means to extend the o (alternative way of writing would be ō) aobachan
Yeah, i think people who are fluent in japanese often pronounce the ''u'' as a long ''o'' so it's not a wrong way to say it but if you say it slowly and properly, it'll be pronounced the way i said it :)
Shin, with the way things are heading this stroke is about to come pretty soon