Additionally, he showed that Proto-Semitic restricted a sequence of two identical consonants in the first and second position of the triliteral root.
ɐdˈɪʃənəli, hiː ʃˈoʊd ðæt pɹˈoʊɾoʊsɛmˈɪɾɪk ɹᵻstɹˈɪktᵻd ɐ sˈiːkwəns ʌv tˈuː aɪdˈɛntɪkəl kˈɑːnsənənts ɪnðə fˈɜːst ænd sˈɛkənd pəzˈɪʃən ʌvðə tɹˈaɪlɪɾɚɹəl ɹˈuːt.