Lack of Vowel Reduction in Southern Brazilian Portuguese

 In parts of southern Brazil, the unstressed mid vowels retain their full value. In other words, they are neither raised nor reduced. This is especially true of rural areas with significant immigration from Germany, Italy and Slavic countries.

The words importante (important) and carro (car) are pronounced with word-final high vowels in most of Brazil. This is also true in Portugal. However, in parts of southern Brazil, they are mid vowels. 

This phonetic characteristic is considered conservative. There may be two factors to explain it. Southern Brazil received many immigrants who spoke German, Italian and Slavic languages. The phonetic structure of their languages reinforced the articulation of unreduced vowels. Another is the geographical proximity to Spanish. The south has borders with Uruguay and Argentina. Constant historical contact with Spanish, a language that completely lacks vowel reduction, further stabilized the preservation of unstressed mid vowels in the region.

Vowel reduction, also known as vowel raising, is common in Portuguese. However, it is often resisted in the dialects of southern Brazil. This may be explained by the arrival of immigrants whose languages did not have vowel reduction and by the geographic proximity to Spanish.