I have 2 boys, they are 7 years old. One of them developed this habit lately in the last 3 months maybe that its been prominent to me. I have tried telling him to stop and ignoring him, but hes getting worse. So someone recommended I put him in another room away from me when Im talking. I started gating him in the living room where he can sit on the back of the chair and see me but hes not near me. It quiets him right down. Ive been doing it every time he starts for only the past 5 days and he seems to be getting the hint. This behavior is unacceptable. Period. Luckily hes catching on quickly.
Good Luck to you!