However, some Austroasiatic languages have lost the register contrast by evolving more diphthongs or in a few cases, such as Vietnamese, tonogenesis.
haʊˈɛvɚ, sˌʌm ˌɔːstɹoʊsɪˈæɾɪk lˈæŋɡwɪdʒᵻz hæv lˈɔst ðə ɹˈɛdʒɪstɚ kˈɑːntɹæst baɪ ɪvˈɑːlvɪŋ mˈoːɹ dˈɪfθɑːŋz ɔːɹ ɪn ɐ fjˈuː kˈeɪsᵻz, sˈʌtʃ ɐz vˌiːɛtnəmˈiːz, tˌɑːnoʊdʒˈɛnᵻsˌɪs.