Vowel Spaces and Systems*
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* Vowel spaces and systems Doug Hitch Whitehorse, Yukon Human language uses two kinds of vowel space: acoustic defined by the F1 vs. F2 quadrilateral, and psychological defined by spatial features (high, low, back, front) which themselves are derived in relation to an often extralinguistic neutral vowel. Lip rounding is not a primary feature of vowel systems. Phonetically front rounded and back unrounded vowels may serve in the psychological space as central vowels. Spatial features define vocalic planes with between two and nine vowels. The interplay between the asymmetrical acoustic space and the symmetrical psychological space produces the known variety in size and shape of vowel systems among the world’s languages. 1 Introduction A vowel may be described in several ways, through the physiology of articulation (articulatory phonetics), through acoustic properties (acoustic phonetics), and through psychologically distinctive traits (phonemics). In my view, for the description of vowel systems, only acoustics and psychology are relevant. Beyond the facts that vowels have to be humanly produceable and hearable, physiology is not relevant to the description of phonemic vowel systems. In spite of this, certain descriptive terms that are historically based on articulation, high (close), low (open), back, front, and round are retained for consistency with tradition and to simplify the presentation. As is well-known, the number of possible shapes of vowel systems in the world’s languages is relatively limited. Twenty-one shapes are presented here and, depending on the analysis, the number will be a little lower or higher. The number and shape of distinct configurations is limited by the interplay of two sets of parameters, acoustic and psychological. 1.1 Purpose The analytical system presented here has both theoretical and descriptive applications. It helps us to better understand how vowel systems work. It makes reference only to acoustic phonetics and not at all to articulatory phonetics. Because of the strict reliance on acoustics, it bears directly on the debate concerning the definition of distinctive features. If one component of the phonology, the vowels, can be successfully defined using only acoustic parameters, this supports the view that all distinctive features are acoustic. Several theoretical claims should be testable. For instance, it is claimed that no vocalic plane will feature more than three degrees of phonemic height or depth. Language descriptions where four or more phonemic contrasts on one axis have been claimed should be subject to reanalysis. Several such cases have been addressed below. An unorthodox claim is that languages can have a vocalic plane containing front rounded vowels like /y ø œ/. Some support is given here, but ideally one would like to find a range of languages where vowels on such a plane behave as a natural class. * This is a study I have been intending to write for a long time. The idea was originally inspired about 40 years ago by “Typology and universals in vowel systems” by John Crothers (1978). In the intervening years I have not been a student of phonological theory and the first draft was written in ignorance of some relevant scholarship. An anonymous TWPL reviewer has greatly helped make this paper look less like it was written on a desert island. The TWPL editor, Ruth Maddeaux, made significant contributions to the organization and presentation. Toronto Working Papers in Linguistics (TWPL), Volume 38 ©2017 Doug Hitch DOUG HITCH This theory simplifies the analysis and description of particular languages. It enables a principle- based typology of possible vowel systems. Every vowel system will conform to one of these patterns. Currently, a typical description of a language contains an IPA-style vocalic trapezoid with the vowels arranged according to acoustic phonetic properties. Alongside this, there should now be one or more square vocalic planes representing psychological properties. Currently descriptions are both phonetic and phonemic, but the use of planes may be a useful improvement. 2 Vowel system acoustics The acoustic analysis of vowels and vowel systems depends on the intersection of the formants F1 and F2. Low vowels have a higher frequency F1 while high vowels have a lower F1. Back vowels have a lower F2 frequency, while front vowels have higher F2 frequency. Figure 1 plots IPA front unrounded vowels, back rounded vowels, and most low unrounded vowels, as pronounced by Bruce Hayes of UCLA. Figure 1: F1 and F2 of some IPA vowels.1 The acoustic analysis of vowels seen in Figure 1 is now usually schematized as a quadrilateral (also called trapezoid or trapezium). In Figure 2 a quadrilateral is superimposed on the chart of Figure 1. 1 http://www.linguistics.ucla.edu/people/hayes/103/Charts/VChart/, accessed 10 Jan 2017. 2 VOWEL SPACES AND SYSTEMS Figure 2: Acoustic quadrilateral The two-dimensional space defined by the quadrilateral is not abstract but physically real. It defines the physical limits of vowel production for a particular speaker. Bruce Hayes will not normally pronounce a vowel with F1 lower than [i] or [u], that is, above the top of the quadrilateral. Similarly, he will not in normal speech produce a vowel with an F1 higher than those along the bottom of the quadrilateral. The sides of the shape require reference to both formants. For instance, there will not be a vowel with the F1 of [e] and a higher F2, or with the F1 of [o] and a lower F2. All vowels produced by this speaker will fall within the acoustic space defined by the quadrilateral. It is standard practice to use a quadrilateral with a right angle at the bottom right corner in the presentation of vowel qualities as in the well known IPA trapezium of Figure 3. Figure 3: IPA vowel trapezium2 While the shape of the quadrilateral may vary by presenter, every presentation shares similar aspects. The left or front line is always longer than the right or back line, and the top or high line is always longer than the bottom or low line which is the shortest of the four. The acoustic quadrilateral is asymmetrical. 2 https://www.internationalphoneticassociation.org/content/ipa-vowels, accessed 10 Jan 2017. 3 DOUG HITCH 2.1 Vowel system psychology In addition to describing the vowel space in terms of acoustic properties, F1 vs. F2, within individual languages it is useful to describe the space in terms of psychologically distinctive properties. These properties do ultimately rest on acoustics but they are distinguished by the mind and organized by the mind into binary oppositions according to certain principles. The first principle is that of the phonetically neutral vowel. It is assumed that all speakers can produce and recognize a neutral vowel. This is a vowel made when the articulatory apparatus is at rest except for the vibration of the glottis. It is the vowel heard when a speaker, uncertain of what to say, says uh [ə], sometimes in a long, drawn-out fashion, or um [əm]. It is common in extra-linguistic expressions, often with a non-spatial phonetic feature added, like nasalization in English unh-unh ‘no’ or creaky voice in ugh ‘that’s disgusting’. Speakers of languages with no phonemic /ə/ may still produce phonetic [ə] and recognize it in extra-linguistic situations. A second principle is that all phonemic vowels are distinguished in relation to the phonetically neutral vowel. A prototypically low vowel will have a higher F1 than the neutral vowel; a high vowel will have a lower F1. Similarly, a front vowel will have a higher F2 and a back vowel a lower F2. A useful and appropriate way to visualize the psychological or psycho-acoustic space created by these principles is by comparing the geometry of geographic directions as illustrated in the map in Figure 4. Figure 4: Directions from the starting point NW N NE W here E SW S SE By convention, the direction north is at the top of the map. The entire top edge of the map represents its northern region. Similarly, there are eastern, western and southern regions. All regions are defined in relation to the neutral starting point which is given as ‘here’ in Figure 4. Two directions overlap at each of the four corners, giving northwest (NW), northeast (NE), southwest (SW), and southeast (SE) regions or corners. The regions along the edges of the map and between the corners are defined by a single direction, north (N), south (S), east (E) and west (W). This arrangement creates nine regions; one neutral region and eight regions defined in relation to the neutral region. The psychological vowel geography is essentially identical, as illustrated in Figure 5. Figure 5: The nine vowel regions high high high front back front ə back low low low front back This principle-derived vowel space geometry has useful implications. One is that no language will exhibit more than three degrees of height or depth as defined purely in spatial terms. It implies that descriptions of languages which assume more than three degrees of phonemic height or backness are somehow defective. Ladefoged and Maddieson (1996: 289) mention Danish as a candidate for exhibiting four degrees of height. But other analyses of this language are possible. For instance, Grønnum (1998: 101) 4 VOWEL SPACES AND SYSTEMS lists ten vowel phonemes, “/i e ɛ a y ø œ u o ɔ/”. If the front rounded vowels /y ø œ/ occupy a secondary plane (see §2.4 below), then there are seven vowels defined purely with spatial features on the primary plane as shown in Figure 6. Figure 6: Danish phonemic vowel space i u e o ɛ a ɔ Ladefoged and Maddieson (1996: 289–290) also mention that the dialect of Bavarian spoken in Amstetten, Austria may have five vowel heights.