An Acoustic Study of Underspecified Vowels in Turkish

Abstract

This paper examines the acoustics of underspecification and vowel harmony (VH) in Turkish. In Turkish, vowels in suffixes that change according to VH rules are widely believed to be underspecified for rounding and/or backness. Underspecification has previously been thought to persist in the acoustic realization of underspecified segments. In the present study, it was hypothesized that underspecification in Turkish vowels persists in their acoustic realization even after specification due to incomplete specification and that harmonizing vowels assimilate to particular vowel categories rather than the trigger vowels themselves. An experiment was run comparing underspecified suffix vowels to their specified counterparts in roots. Of the vowels underspecified for rounding, unrounded high vowels had a significantly higher F2 and [i] had a significantly lower F2 compared to their specified counterparts at all three points of measurement. This could be a case of enhancement, where the features of the first vowel are copied and enhanced to optimize perception. No such differences were found for vowels underspecified for backness. Additional effects of specification were found to be significant in individual specified/underspecified vowel pairs in terms of F2. A second experiment was run to determine if VH is a coarticulatory process in which the harmonizing vowel assimilates to the trigger vowel itself. Of the high underspecified suffix vowels, [u] was found to differ significantly according to the height of the preceding vowel, while low suffix vowels differed significantly according to the rounding of the preceding vowel. The results of the second experiment showed that coarticulation is an active process in Turkish which affects underspecified vowels as well. It was concluded that coarticulation and specification are two separate processes. Specification is a process uniform throughout the vowel, starting from a position neutral to the underspecified features and eventually overshooting them, while coarticulation is a dynamic process, affecting the area closest to the trigger vowel.