Variable Pronunciation with Suffixation

Suffixes such as -ful, -ly and -ness can attach to many roots. However, the pronunciation of the final vowel of the root varies. Let us look at a few examples.

A number of suffixes can combine with beauty to produce words such as beautify, beautiful and beautification. In these cases the final vowel of beauty is pronounced as a schwa in the forms with suffixation. However, this is not the case with the compound beauty queen. Here the final vowel of beauty is pronounced as a high front tense vowel.

The suffix -ly can produce many adverbs. A few examples include angrily, crazily  and happily. In these cases the final vowel of angry, crazy and happy becomes a schwa in the forms with suffixation.

In the word merciful, the penultimate vowel is pronounced as a schwa. This is the same as in beautiful. However, in words such as friendliness and happiness the penultimate vowel is not realized as a schwa but rather as a high front tense vowel. The penultimate vowel of happily is different from the penultimate vowel of happiness.

How can we explain this disparity? Why are the penultimate vowels of forms such as happily and happiness different? In both cases the penultimate vowel is unstressed and the preceding syllable is stressed. The environments are very similar. The notable difference is in the segments of the final syllable. In happiness the final syllable is CVC and in happily it is CV. Thus we see a difference in syllable weight.

It is the case that with the final light syllable of happily, the penultimate vowel becomes a schwa, but with the final heavy syllable of happiness, the penultimate vowel remains a high front vowel. Though  -ness is a bound morpheme, for the purposes of pronunciation it functions as the second word of a compound as in beauty queen.

The final vowel of words such as beauty and happy becomes a schwa in forms with the derivational suffixes -ful and -ly such as beautiful and happily. However, the pronunciation of the final vowel does not change in forms with the suffix -ness as in friendliness and happiness. This reality counters the principle of the regularity of sound change.