Labio-dental(唇齿音) The lower lip is the active articulator and the upper teeth are the passive articulator English labio-dental sounds include f and 2021/2/23 102021/2/23 10 Labio-dental (唇齿音) • The lower lip is the active articulator and the upper teeth are the passive articulator. English labio-dental sounds include [f] and [v]