Vowel inventories in the languages of Frēdauon
This research paper provides an exploratory study of the phonemic vowel quality inventories in the languages of Frēdauon. A bimodal distribution is diagnosed with three vowels and five vowels being the most common inventory sizes. Examples data of typical vowel quality inventories and outliers are discussed seperately. The outliers are explained as resulting from a diachronic process of transphonologization.
1. Introduction
Vowels are the most sonorous category of sounds in languages. They canonically form the nucleus of a syllable and include the sounds /a, e, i, o, u/ in many languages. Vowel quality is usually defined as including vowel backness, vowel height, lip rounding, and tenseness. Vowel backness and vowel height can be described articulatorily as refering to the position of the highest point of the tongue while producing the vowel. Some languages also distinguish vowels based on the presence or absence of a rounding gesture produced by the lips during the articulation of the vowel. Tenseness is less easily explained and has been traditionally linked to the tenseness or laxness of the muscles involved in articulation. In some languages a similar distinction has been linked to the relative position of the tongue root.
Acoustically, vowel height is correlated with the first maximum of acoustic energy in the (lower) frequency (F1), whereas vowel backness influences the second formant (F2). Lip rounding is linked to both the second and the third formant. Tenseness influences both the first and the second formant.
In the following table the vowel quality inventory of Kobardon (Northern, Northern Mountains) is given. Two front vowels /i, e/ , a central vowel /a/, and two back vowels /o, u/ are distinguished by backness. The two back vowels are also rounded. On the height axis, high vowel /i, u/ are distinguished from mid vowels /e, o/ and the low vowel /a/. Tenseness is not employed contrastively, here.
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Vowels in Kobardon
front central back
high /i/ /u/
mid /e/ /o/
low /a/
A variety of distinctions are ignored in descriptions of vowel inventories and in this study specifically. Languages also distinguish vowel length in their vowel phoneme inventories, manifested mainly by phonetic duration differences. Additionally, vowels can be produced with additional airflow escaping through the nose, resulting in so-called nasal vowels. A variety of distinctions are related to voice, i.e. the vibrtation of the glottal folds. None of these distinctions will be discussed here any further.
It should be noted that any phonemic inventory always involves a certain abstraction. Vowels can be judged to be contrastive based on minimal pairs and this can be incorporated into an analysis. A distinction is said to be contrastive, if there is some pair of words that is only distinguished through this feature. The actual phonetic realization might occur for different speakers or in different lingustic and metalinguistic contexts. In Kobardon for example, additional phonetic vowels [ɪ, ʊ] can occur. These are restricted to a specific position and can be analyzed as resulting from reduction of mid and high vowels /i, u, e, o/ in phrasally unaccented positions. More than one analysis might suit the same set of data and there is no guarantee that there is a unique `correct' or superiour analysis for any given vowel system in a language.
2. Methodology
A sample was generated that included any language from Frēdauon for which sufficient documentation is available that includes both a language endonym and a vowel inventory. The language was neither controlled for language family nor for linguistic area. This yielded a sample size of N=99 languages.
The number of vowel phonemes was counted and noted seperatedly for each language. If no seperate vowel phoneme inventory was provided, a vowel phoneme inventory was generated by seperating vowel inventories and consonant inventories. The count of languages for each number of vowels was then determined.
3. Results
The following graph shows the results of this study. The number vowel phonemes in the languages of Frēdauon ranges from a single vowel (n=1, Dhā́ddwã) to 16 vowels (n=1, Late Omlüt). The mode and the median coincide at a five vowel system, which is found in 27 languages. The arithmetical mean is at 5.44 and the standard deviation is at 2.512.

Two further local maxima with more than one language show up in the study. There are 18 languages with three vowels and four languages with ten vowels. In other words, languages with four vowels or nine vowels are less common than languages with minimally higher or lower vowel counts. If all languages deviating no more than one standard deviation from the mean, 80 languages would be included in this average category. Three languages would be in a category with smaller than average vowel inventories and 16 languages would be in a category with larger vowel inventories.
Kobardon has already been shown as a typical five vowel inventory. The second most common vowel inventory is a triple. One representative example is Tlák'áta (Black languages, various places). The vowels are distributed evenly across the vowel space, only occuring at the edgemost corners. The front high vowel contrasts in both rounding and backness with the back rounded vowel /u/. The only low vowel /a/ on the other hand is also the only central vowel.
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Vowels in Tlák'áta
front central back
high /i/ /u/
low /a/
Apart from the typical vowel inventories, there are also some outliers. These can be explained by a diachronic development of transphonologization. Transphonologization refers to the shifting of a phonological contrast from one segment to another or from one phonological dimension to another on the same segment. In the cases of very small inventories, the vowel quality contrasts have shifted from vowels onto consonants. In cases of large vowel inventories, several phonological dimensions have been diachronically merged into vowel quality distinctions
Dhā́ddwã (isolate, Great Western Bay) has been analyzed as having a single underlying vowel whose vowel quality is completely determined by phonological context. Note that Dhā́ddwã has labial/labialized and palatal/palatalized sounds that influence the backness and rounding of the surrounding vowels. The backness and rounding dimensions of vowels have become transphonologized onto the consonants.
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Vowels in Dhā́ddwã
front central back
low /a/
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Vowels in Late Omlüt
front central back
unrounded rounded unrounded unrounded rounded
high tense /i/ /y/ /ɯ/ /u/
high lax /ʏ/ /ʊ/
mid tense /e/ /ɤ/ /o/
mid lax /ɛ/ /ə/ /ʌ/ /ɔ/
low /æ/ /ɑ/