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Complementary distribution

The notion of ‘phoneme’ is sufficiently abstract that many students have a hard time getting hold of just when you have two diffierent phonemes, and when you’re looking at allophones. The idea of distributions or environments seems obvious to us. Of course, these environments are defined by the properties of the sounds/signs around them, and the distribution of an allophone is the set of the environments where that allophone occurs. But remember that your students may be just learning about how to define the linguistic properties of a sound or a manual sign. Understanding in what terms to define the environments will not come automatically to them, as they may be struggling to keep the differences between features, allophones and phonemes straight, not to mention where each of these terms is relevant.

(1) Here are a few ways of expressing a definition of complementary distribution. They all require you to explain some background. For example, what does ‘mutually exclusive’ mean? ‘segment’? ‘distribution’?

(2) Complementary distribution is the mutually exclusive relationship between two phonetically similar segments. It exists when one segment occurs in an environment where the other segment never occurs.
Relation between sounds or forms whose distributions do not overlap. Thus in southern British English (RP), an unaspirated [p] appears after an initial [s], e.g. in [spin] (spin); an aspirated [ph] e.g. initially in [ph i n]; but there is no context in which both would be normal. Therefore they are in complementary distribution, and therefore, in part, they are described as allophones of the same phoneme.

(3) Think about a soccer team: Each player standing on the field has her own ‘environment’ where she waits for the kickoff. This environment is the territory where she launches an offensive strategy, and the territory that she defends when the opposite team is approaching her team’s goal. She may be the goalie, or the fullback, or right halfback. Her position or territory is defined relative to the center line and right or left halves of the field, or relative to her team’s goal. Any single player with any of these territories is not the team – the team is the whole collection of players with their territories. Think of the phoneme like the team, and the allophones like the players. Allophones also have their ‘territory’ or linguistic environments that they cover, and no allophones of a phoneme will have overlapping territories. These territories, or ‘environments’, are defined in terms of the relevant linguistic features of the sounds near the allophone. These ‘relevant linguistic features’ are features related to voicing, place and manner of the sounds, or handshape, location, and orientation of a signed segment. When one sound or signed segment enters the territory of another, you know they are on opposing teams, i.e., members of different phonemes. When you define the territory of an allophone, you are defining its distribution, the set of places within words in a language where the allophone appears.

Here is an example:

* [spæt] [phæt] *[sphæt] *[pæt]
* [spul] [phul] *[sphul] *[pul]
[ph] and [p] are in complementary distribution. [p], or ‘unaspirated p’, doesn’t occur word-initially, but ‘aspirated p’ does. An English speaker hears these sounds as the same sound; even if some speakers pronounce words with unaspriated [p] at the beginning, other speakers won’t hear those pronunciations as different words with different meanings.

The set of contexts within sentences or within words in which a unit or class of units can appear. For example, nouns can fill certain contexts within sentences; these contexts can be defined as a set of grammatical roles like ‘subject’ or ‘object. The contexts for allophones can be defined in terms of features of the sounds around them, or properties of syllables or words. For example, ‘word-initial’ or ‘syllable-final’; ‘after consonants’ or ‘before vowels’; ‘before voiced fricatives’ or ‘after front vowels’.

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Last updated September 21, 2003