Acoustic Analysis for Raising /ɑ/ to [u] in the Context of –n in the Contemporary Persian Language

This paper investigates the raising of the low back vowel /ɑ/ to high back vowel [u] in the context of nasal consonant –n within the experimental phonology framework of Beddor (1983). There exists an inconstancy in Persian. The raising process happens in some cases but not in others. Investigating the source of this inconsistency, the paper attempts to represent a phonetic explanation for the phenomenon. Focusing on the acoustic parameters of nasalization and their effects on vowel height the phonological pattern of this phenomenon  was determined . The pattern proved to be a style–dependent process which takes place only in colloquial Persian. Two kinds of speech data were acoustically analyzed: (1) Four words in formal style including the sequence [ãn] and the same four words in colloquial style including the sequence [ũn]; (2) Three sustained speech sounds [a], [u] and [n]. All the words and sounds were pronounced in isolation by five male Persian speakers. The results showed that according to parameters F1, F2 and F2-F1, while nasalization has no decreasing effect on the F1 of the low back nasalized vowel, it increases the F1 of the high back nasalized vowel compared to its corresponding oral vowel. In addition, the low back nasalized vowel appears to be further front than its corresponding oral vowel. Finally, since the value of acoustic salience for [ũn] was significantly higher than the same value for [ãn], it was concluded that this style-dependent phonological raising makes the sequence more perceptible in the colloquial style.