LING150/University of Oregon

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3.1.1. Regular sound changes

3.1.2. Understanding rules

Up to this point in the course, you have been able to parse words into morphemes and allomorphs that you have memorized. This is fairly straightforward as long as you know all the assigned morphemes. But often, when two morphemes are put together, the sounds in one morpheme will affect the other, causing it to change its form into an allomorph that you have not memorized! Since these changes happen regularly in certain situations, linguists write rules which describe the alternation. This way, you don't need to memorize dozens of different allomorphs. You can simply learn the rule and apply it over and over with many morphemes in a variety of different situations.

One frequent allomorphy process that was discussed is Unit 2 is assimilation. Sounds often change to become more like surrounding sounds. The alveolar nasal [n], in particular, almost always assimilates to the place of a following stop or nasal. So an [n] usually changes to the bilabial nasal [m] when the next sound is a bilabial. You can expect than any morpheme you have studied that ends in "n" will undergo nasal assimilation in this situation.

In most words borrowed from Latin and French, the spelling matches the pronunciation; however with newly coined words, it usually does not. For example, the word "input" does not show nasal assimilation in the spelling. Listen carefully to the way people pronounce this word in ordinary conversation. You'll find that often speakers actually say . The phonetic alteration occurs regularly and predictably regardless of the spelling! Words which existed before the rise of nearly universal literacy usually reflect the nasal assimilation in their spelling; more recently coined words may not, and perhaps never will.

Assimilation (of which there are several types) is probably the most frequent type of predictable allomorphy. The other most frequent types of predictable allomorphy involve insertion of sounds or the deletion of sounds.

3.1.2. Understanding rules

The rules which describe predictable allomorphy have three necessary components

1. the sound affected,
2. the new sound (the one which the affected sound changes to),
3. the context in which the change occurs (i.e. the nearby sounds that cause the change).

These three components are put together in sentence that is stated in a particular way:

The sound affected becomes the new sound when it occurs in the context of critical nearby sounds.

Linguistics usually write these rules using special shorthand symbols:

the sound affected --> the new sound / in the context of critical nearby sounds.

For the nasal assimilation rule, we could write

n --> m / __ p, b, m

Here, n is the sound affected, m is the new sound, and p, b and m are the critical nearby sounds. The underline in the context component of the rule stands for the sound affected. The position of the underline relative to the critical sounds indicates the position of the affected sound. This rule indicates that the n must come before the critical nearby sound.

When writing rules, sounds or spellings are given in lower cases letters. The uppercase letters V and C stand for VOWEL and CONSONANT, respectively. They're used when the rule affects any or all vowels or consonants. The symbol ø indicates "no sound"

TYPO IN TEXTBOOK Rule 5. Vowel Deletion is incorrect. It should read: V --> ø __r + V This rule affects morphemes in which a vowel comes before an r.

Copyright 1998 by the Department of Linguistics, University of Oregon.