Carol needs to raise her hand when Bob moves to topic 3. A raised hand signal seems to transcend cultures, and it lets the speakers and all listeners know you

Carol needs to raise her hand when Bob moves to topic 3. A raised hand signal seems to transcend cultures, and it lets the speakers and all listeners know you have something important to say but you're being polite and letting them finish. And if the speaker/chair ignores you, it makes them look rude.