1. The “Xứ Nẫu” people are known as the ones pronouncing the diphthong of “âu” in their speech. Phu Yen and Binh Dinh, the two provinces of Central Vietnam, are located closely along at hand along the coast, not only have the same features relating to the terrains, living customs, but also their similar unique pronunciation, using the sound “âu”. In addition to words with the original sound “âu”, such as “đi đâu” (Where do you go), “ruộng sâu ruộng cạn” (water field dry field), “con ong nâu” (a brown bee), “làm gì lâu vậy” (How long it is to do!), “chó sủa gâu gâu” (a dog barks “woof, woof”), there are a lot of words regarded as the same diphthong “âu” as the ones mentioned above. However, it is the transformation from the sound “ôi” into “âu”, for instances, trái ổi → trái ẩu (guava), mặc kệ tôi→ Kệ nẫu/ Kệ tui (none of your business!), thiên lôi→ Thiên lâu (God of thunder), bệnh rồi→ bệnh rầu (I’m sick.), etc.