Turkish vowel harmony is very systematic, but in a little-studied class of words, appears to break down. I propose that this apparent harmony failure is actually covert harmony, or exceptional transparency.

Background: The backness of vowels in Turkish suffixes is determined by the backness of the nearest vowel in the word they attach to (1).

(1) Nom. Dative Gloss

a. kadran → kadran-a, *kadran-e 'clockface'

b. beden → beden-e, *beden-a 'body'

Harmony within roots is often violated, but harmony between suffixes and the nearest root vowel is extremely robust (2). Nonetheless, in certain roots, /a/ exceptionally behaves as transparent and suffixes must surface with front vowels (3).

(2) Singular Plural Gloss

a. kitap → kitap-lar, *kitap-ler 'book'

b. kahve → kahve-ler, *kahve-lar 'coffee'

(3)

a. harf → harf-ler, *harf-lar 'letters'

b. dikkat → dikkat-ler, *dikkat-lar 'attentions'

To account for this exceptional transparency, I extend Smolensky's (2006) headed feature domains theory, and propose that the input to phonology contains headless feature domains.

Proposal: Existing theories of vowel harmony require a segmental harmony trigger. But harf contains no [-back] segment to head a front feature domain and select front suffixes, so harf-ler remains unexplainable. Extending Smolensky (2006), I propose that all features are feature domains, which replace traditional segmental feature specifications.

In Turkish, backness domains normally coincide with roots. Alternating suffixes lack their own backness domains and merge into the stem's domain. Exceptional transparency is driven by faithfulness considerations: the root as a whole is a front domain, but it contains /a/ in an embedded back domain. Suffixes are incorporated into the outermost backness domain as usual, resulting in transparency.

(4) (dik(ka)bt)f) + lEr → (dik(ka)btler)f)

Since vowels must realize the backness of their containing domains, high- and mid- vowels cannot occur in conflicting embedded domains. However, as a low vowel, /a/ is more central than the other back vowels, and unlike the other Turkish back vowels, it lacks an exactly height-matched front counterpart phoneme. Perceptual reasons, then, lead the Turkish constraint-ranking to allow only /a/ as an exceptionally transparent vowel. The feature-as-domain analysis of vowel harmony models the selection of front suffixes by harf and dikkat without the need to posit phonetically unrealized front features on consonants, or any other additional apparatus.

Vowel insertion commonly occurs cross-linguistically to break up consonant clusters, particularly in loanwords. The most familiar form of this insertion is the categorical, phonological process of vowel epenthesis, which repairs syllable structure violations. However, gradient, phonetic vowel insertion also occurs in many languages. This phenomenon, known as vowel intrusion, occurs when speakers employ a gestural timing that results in an open transition between the consonants in the cluster. The resulting intrusive vowel is not a phonological segment, and therefore lacks gestural and durational targets.

This dissertation presents a case study of vowel intrusion in Turkish onset clusters, which occur in European loanwords. The non-lexical vowels in these clusters have previously been described as epenthetic vowels whose quality is categorically determined by the following lexical vowel, in a process of regressive vowel harmony. I present new evidence from experimental, corpus, and elicitation data, that the non-lexical vowel in Turkish onset clusters lacks a gestural or durational target, and does not form a syllable nucleus—distinguishing characteristics of intrusive vowels. Gestural and acoustic data comes from an ultrasound production study, which shows that the non-lexical vowel is gradiently present; does not achieve the same gestural and durational targets as lexical vowels; and is more affected by coarticulation.

A corpus study extends the investigation to other types of consonant clusters, and finds that the effect of the consonantal environment on the non-lexical vowel can be seen even in broad transcriptions. I also probe the syllabic and metrical status of using two studies of text-setting of /CC/ words. These studies reveal that is more variable and less likely to receive a beat than lexical vowels.

This evidence supports an analysis of Turkish /CC/ words as beginning with onset clusters. I present a coupled oscillator representation of vowel intrusion and onset clusters, using Optimality Theory and allowing the phonology to refers to both segments and gestures. I also argue that Turkish has historically been reanalyzed as an underlying vowel, but that language-internal variation, as well as increasingly prevalent knowledge of source languages, today maintain its status as an intrusive vowel.