Insights on Vowel Spacing


June 14, 2002

9.1 Introduction

   This chapter presents the results of an analysis of the vowel systems of the 317 languages in the UCLA Phonological Segment Inventory Database (UPSID).


9.2 Preliminaries

(1)   The most prevalent patterns seem to be the so-called “triangular” systems, particularly those of average size, and notably the 5-vowel systems.

(2)   Liljencrants and Lindblom (1972), Lindblom (1975), Terbeek (1977), and Maddieson (1977) proposed different versions of a principle of vowel dispersion. The principle holds that vowels tend to be evenly distributed in the available phonetic space and also widely distributed, within the limitations of the particular system.

(3)   Among the vowel systems of 317 languages, there are some systems in which the vowels are not evenly or widely distributed in the available space. These systems are called “defective vowel systems.”

(4)   There are three possibilities in “defective” vowel systems (Figure 9.1):

The first shows a system with a gap, represented by [ ], in the high back

   region, but with a back mid vowel higher in the phonetic space than the

   corresponding front mid vowel.

The second is that the entire system is rotated with respect to the typical,

   unmarked configuration for a vowel system of a particular size (here, a 5-

   vowel system).

The third illustrates a defective system that is complemented with a vowel

   of unexpected quality in the vicinity of the gap.

(5)   There are also three possibilities in “unbalanced” vowel systems (Figure 9.2):

The vowel adjacent to the gap is farther away from it than would be

   expected from comparison with the paired vowel.

There may be systems in which a vowel of unexpected quality is located

   well away from the vicinity of the gap.

There may be systems which are not open to interpretation as making any

   compensation for the imbalance in the system. These “stationary” systems

   contain a gap.


9.3 Method

(1)   Data

The vowel phonemes in UPSID are represented on a height scale with 5

   basic values ( high, higher mid, mid, lower mid, low).

The vowels are also categorized on a backness scale with 3 values ( front,

   central, back), and on a rounding scale with 2 values ( rounded,unrounded)

There are also additional dimensions pertaining to length, nasalization, pho

   -nation characteristics ( laryngealization, breathiness), and other features (

   r-coloration, lip compression).

The vowels will be discussed in terms of a distinction between peripheral

   and interior vowels. The “peripheral” vowels are the front unrounded, back

   rounded, and low vowels. However, high central vowels constitute the set

   of “interior” vowels.

(2)   Identifying “defective” vowel systems

The 317 languages are tested to identify those which contain gaps in the

   peripheral vowel system.

The test examines whether the 5 major regions along the periphery of the

   vowel space, high front, high back, mid front, mid back, and low central,

   are filled with at least one vowel.

There is an exception: those vowel systems which lack all high vowels or

   all low vowels, but are balanced, should not be classified as defective sys-



9.4 Analysis of defective systems

   Only 43 languages (13.6% of the sample) were found to have vowel systems with

   at least one major gap. These will be discussed below in several parts.

(1)   Four-vowel systems

All 4-vowel systems with one mid vowel are regarded as defective. There are 6 cases: Shasta, Paez, Moxo, bardi, Wichita, and Cayapa.

(2)   Frequency of missing vowels

The missing vowels are generally /e/, /u/, or /o/, never /i/.

The high front and the low central vowels are less likely to be missing than

   the high back rounded vowel, i.e. /a/ and /i/ > /u/.

The high back vowel is more likely to be absent in natural languages than

   either the front or the back mid vowels, i.e. /e/ and /o/ >/u/.

Almost half of the 35 languages which lack a single vowel lack /u/; 9 lack

   /e/, 7 lack /o/, and 2 lack /a/. The implied ranking is therefore:

   { i, a} > {e, o} > u

In addition to the languages which lack a single vowel, 6 lack more than

   one vowel. (Figure 9.3)

(i)                  The most common pattern (5 languages) involves a missing high back vowel and mid front vowel, creating a double gap of positive slope.

(ii)                No language has a gap of negative slope due to the lack of a high front vowel and a mid back vowel.

(iii)               Vertical gaps are also rare: only one language lacks back high and mid vowels.

(3)   Stationary systems

Stationary systems are ones which have a gap that they do not appear to compensate for in any way. All of these happen to be 3 or 4-vowel systems.

There are 9 or perhaps 10 languages which fall under the category of “stationary” systems. They are Klamath, Bardi, Shasta, Paez, Moxo, Campa, Tacana, Hupa, and Mura.

(4)   Complementary vowels

Some of the languages have defective systems that are complemented by a single vowel of unexpected phonetic quality which shares some of the features of the missing vowel.

Vowel systems of this sort can be classified into 3 major types:

Vowels of unexpected backness ([α high, +central])

(i)                  / / for an expected missing mid or low vowel (e.g. in Tagalog, Changchow, Cheremis and Acoma)

(ii)                / / for an expected missing high vowel (e.g. for missing /u/ in Adipon and Cofan)

      Vowels of unexpected lip position ([α high, β back, -β round])

         13 defective systems have a vowel with the same height and backness as

         the missing peripheral vowel, but with the opposite rounding.

(i)                  Only in Bashkir and Khalaj are the complementary vowels ( / / in  each case) embedded in a series.

(ii)                In Gilyak and Island Carib, the complementary role of the mid interior vowel is underscored by the lack of a high interior vowel.

(iii)               Japanese, Nunggubuyu, and Alawa have the sound / / compensating for a missing high back rounded vowel.

(iv)              In another 3 languages, Adzera, Nez Perce, and Amahuaca, only one of two gaps in the peripheral vowel system is complementend

      Vowels of unexpected height ([-α high or –γlow; β back])

(i)                  In the case of non-low vowels we shall define the complementary vowel as the one which lacks a counterpart of equal height and opposite rounding elsewhere in the vowel system. ( There are 3 languages involved: Kunimaipa, Navaho, and Nootka.)

(ii)                In the case of low vowels, the complementary vowel is always the non-central vowel. (There are also 3 languages involved: Taishan, Nez perce, and Ket.)

(5)   Complementary vowels with additional adjustments 

The system is skewed such that one or more of the remaining vowels is found closer to this gap than we would expect, based on the height of the matching vowel(s). Here are 4 languages involved: Gilyak, Cofan, Ocaina, and Bashkir.

(6)   Compensation in the peripheral vowel system

There are some cases of complemented vowel systems whose remaining peripheral vowels are displaced toward the gap as well. These systems thereby achieve an even greater degree of compensation.

Compensations involving a single vowel

   Vowel systems of this sort are very similar to vowel systems with a com-

   plementary peripheral vowel of unexpected height. The main difference is

   that in the latter the vowel shares its region with another peripheral vowel,

   while in the former it is alone in its region of the vowel space.

   There are 8 languages involved: Ocaina, Cofan, Bashkir, Malagasy,

   Mazatec, Cheremis, Amahuaca, and Wichita.

Compensations involving multiple vowels

(i)                  Vowel systems with displacements at more than one point in the peripheral system show an even greater tendency toward dispersion in the vowel space. 2 Languages are involved: Gilyak and Cayapa..

(ii)                When a gap occurs in the peripheral vowel system, some or all of the remaining peripheral vowels are often found to be displaced in the direction of the gap.

(7)   Unevenly spaced vowel systems

Vowels in the remaining systems appear to be distributed unevenly in the phonetic space, contrary to the predictions of any dispersion theory. For example, two languages, Hopi and Auca, constitute the clearest examples of unevenly spaced systems in our sample. Besides, Nootka and Seneca are another languages that might be considered in this class.


9.5 Conclusions

   The great majority of vowel systems in our sample assume configurations

      which are predictable from a theory of vowel dispersion. However, There are

      43 languages which are exceptions to the notion of vowel dispersion.

   The defective systems can be classed into 3 major categories:

(i)                  9 of these 43 languages simply tolerate the gap in the system, showing no evidence of any compensatory shifts.

(ii)                Some 2 to 4 of the languages with major gaps show a displacement of the remaining vowels away from the gap, resulting in an uneven distribution of the vowels.

(iii)               The great majority of the defective systems, at least 30 languages, tend toward a balanced distribution of vowels in the available space.