This article deals with the non-final posttonic vowel subsystem of Brazilian Portuguese, specifically it questions if the high-mid vowels /e, o/ have undergone neutralization in this position. Three accounts have been provided so far to answer this question. Câmara Jr. (1999) proposes that the nonfinal posttonic subsystem is composed of four vowels /i, e, a, u/; Bisol (2003) advocates for a three-vowel subsystem /i, a, u/, and Ribeiro (2007) defends a five-vowel subsystem /i, e, a, o, u/. In this paper, I show that mid-vowel alternation in nonfinal posttonic context is the key to defining what the vowel subsystem is, which must be composed of five vowels /i, e, a, o, u/; however, differently to what has been proposed by Ribeiro (2007) for whom mid-vowel alternation is a case of lexical diffusion, I show that a rule-based approach is more explanatory of the phenomena.

中文翻译：

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语音过程在确定巴西葡萄牙语元音清单中的作用

本文讨论了巴西葡萄牙语的非最后的元音元音子系统，特别是它质疑中高级元音/ e，o /在此位置是否已被中和。到目前为止，已经提供了三个帐户来回答这个问题。CâmaraJr.（1999）提出，非最终的阶调子系统由四个元音/ i，e，a，u /;组成。Bisol（2003）倡导三元音子系统/ i，a，u /，而Ribeiro（2007）捍卫五元音子系统/ i，e，a，o，u /。在本文中，我证明了在非最终语调环境中元音中间的交替是定义元音子系统是什么的关键，元音子系统必须由五个元音/ i，e，a，o，u /组成；但是，与里贝罗（Ribeiro（2007）的建议不同），在这种情况下，元音中间的交替是词汇扩散的情况，