Roots that may have contained sequences that were possible in Proto-Afroasiatic but are disallowed in the daughter languages are assumed to have undergone consonant dissimilation or assimilation.
ɹˈuːts ðæt mˌeɪhɐv kəntˈeɪnd sˈiːkwənsᵻz ðæt wɜː pˈɑːsᵻbəl ɪn pɹˈoʊɾoʊˌæfɹoʊˌeɪsɪˈæɾɪk bˌʌt ɑːɹ dˌɪsɐlˈaʊd ɪnðə dˈɔːɾɚ lˈæŋɡwɪdʒᵻz ɑːɹ ɐsˈuːmd tə hæv ˌʌndɚɡˈɑːn kˈɑːnsənənt dɪsˌɪmɪlˈeɪʃən ɔːɹ ɐsˌɪmɪlˈeɪʃən.