There are different ways that people may spell the name "Ostroff," but the most common spelling is /ˈɑːstrɑf/. The first syllable is pronounced like "ost," with the "o" sound as in "go." The second syllable has the same vowel sound as in "lot," and the "r" is pronounced with a slight rhotic sound. The final two letters "off" are pronounced with an "aw" sound as in "law." It's important to remember that there are different ways to spell names, and it's always best to ask the person directly for their preferred spelling.