 Similarly, at one point in the design, there was an alternate "mouth" assembly consisting of a wooden box with a pair of hinged shutters that acted as lips.Inside the box resided a hinged, wooden, string-operated flap that acted as a tongue.The purpose of this assembly was to mimic the mouth and tongue in the construction of plosives such as "b” and "d”, but was later removed when Kempelen recognized that without a proper tongue, the machine would never be able to produce /t/, /d/, /k/ and /ɡ/.