Several Omotic languages have "sibilant harmony", meaning that all sibilants (s, sh, z, ts, etc.) in a word must match.
sˈɛvɹəl ɑːmˈɑːɾɪk lˈæŋɡwɪdʒᵻz hˈæv "sˈɪbɪlənt hˈɑːɹməni", mˈiːnɪŋ ðæt ˈɔːl sˈɪbɪlənts ˈɛs, ˌɛsˈeɪtʃ, zˈiː, tˌiːˈɛs, ɛtsˈɛtɹə.ɪn ɐ wˈɜːd mˈʌst mˈætʃ.