The shape of the tongue control reminds me a lot of the rhombus in https://en.wikipedia.org/wiki/International_Phonetic_Alphabet#Vowels https://en.wikipedia.org

The shape of the tongue control reminds me a lot of the rhombus in https://en.wikipedia.org/wiki/International_Phonetic_Alphabet#Vowels https://en.wikipedia.org/wiki/International_Phonetic_Alphabe... ... which is because the latter was patterned after the shape of the mouth.