Language variation

            There are various mutually intelligible regional varieties (or dialects), the main four being:

Vietnamese has traditionally been divided into three dialect regions: North, Central, and South. However, Michel Fergus and Nguyễn Tài Cẩn offer evidence for considering a North-Central region separate from Central. The term Haut-Annam refers to dialects spoken from northern Nghệ An Province to southern (former) Thừa Thiên Province that preserve archaic features (like consonant clusters and undiphthongized vowels) that have been lost in other modern dialects.

These dialect regions differ mostly in their sound systems (see below), but also in vocabulary (including basic vocabulary, non-basic vocabulary, and grammatical words) and grammar.^[14] The North-central and Central regional varieties, which have a significant amount of vocabulary differences, are generally less mutually intelligible to Northern and Southern speakers. There is less internal variation within the Southern region than the other regions due to its relatively late settlement by Vietnamese speakers (in around the end of the 15th century). The North-central region is particularly conservative. Along the coastal areas, regional variation has been neutralized to a certain extent while more mountainous regions preserve more variation. As for sociolinguistic attitudes, the North-central varieties are often felt to be "peculiar" or "difficult to understand" by speakers of other dialects.

It should be noted that the large movements of people between North and South beginning in the mid-20th century and continuing to this day have resulted in a significant number of Southern residents speaking in the Northern accent/dialect and to a lesser extent, Northern residents speaking in the Southern accent/dialect. Following the Geneva Accords of 1954 that called for the "temporary" division of the country, almost a million Northern speakers (mainly from Hanoi and the surrounding Red River Delta areas) moved South (mainly to Saigon, now Ho Chi Minh City, and the surrounding areas.) About a third of that number of people made the move in the reverse direction.

Following the reunification of Vietnam in 1975-76, Northern and North-Central speakers from the densely populated Red River Delta and the traditionally poorer provinces of Nghe An, Ha Tinh and Quang Binh have continued to move South to look for better economic opportunities. Additionally, government and military personnel are posted to various locations throughout the country, often away from their home regions. More recently, the growth of the free market system have resulted in business people and tourists traveling to distant parts of Vietnam. These movements have resulted in some small blending of the dialects but more significantly, have made the Northern dialect more easily understood in the South and vice versa. It is also interesting to note that most Southerners, when singing modern/popular Vietnamese songs, would do so in the Northern accent. This is true in Vietnam as well as in the overseas Vietnamese communities.

The syllable-initial ch and tr digraphs are pronounced distinctly in North-central, Central, and Southern varieties, but are merged in Northern varieties (i.e. they are both pronounced the same way). The North-central varieties preserve three distinct pronunciations for d, gi, and r whereas the North has a three-way merger and the Central and South have a merger of d and gi while keeping r distinct. At the end of syllables, palatals ch and nh have merged with alveolars t and n, which, in turn, have also partially merged with velars c and ng in Central and Southern varieties.

Sources wikipedia.org