Schwa in Pairs with Affixation

The schwa in English is restricted to unstressed syllables. It is a phonetic variant of English vowel phonemes. It appears in many word pairs. This is illustrated with the following ten pairs:

abolish abolition

biology biological

commerce commercial

drama dramatic

family familiar

generous generosity

moderate moderation

personal personality

photo photographer

prophet prophetic

In the word abolish, the schwa appears in the first syllable. In the noun abolition, however, the schwa is in the second syllable. The stress is in different syllables, but in both words it is penultimate.

With biology/biological, the schwa also appears in different syllables. In the first word, it is in the third syllable, and in the second word, it appears in both the second and fifth syllables. The front high vowel does not become a schwa.

In the third pair, the schwa appears in the first syllable of commercial. It appears in the final syllable of drama and in the first syllable of dramatic. The first syllable of family has no schwa, but the first syllable of familiar does.

The schwa appears in the second and third syllables of generous. However, in the word generosity, the schwa appears in the second syllable, but not in the third. The fourth syllable can be pronounced with a schwa or with a high front unrounded law vowel.

In the pair moderate/moderation, the schwa appears in the second syllable of both words. However, the third syllable of moderate is a schwa in the adjective but not in the verb. The noun moderation has no schwa in the third syllable.

The second and third syllables of personal have the schwa. In the word personality, the schwa occurs in the second syllable, but not in the third. It cannot appear in the third syllable because it is stressed.

No schwa occurs in the word photo. Though the second syllable is unstressed, it remains a diphthong. However, the schwa occurs in the first and third syllables of photographer.

With the word pair prophet/prophetic, the schwa occurs in the second syllable of prophet and the first syllable of prophetic. The third syllable of prophetic is a not a schwa but a high front unrounded lax vowel. Both words have penultimate stress.

The schwa is a very common vowel of English. In related words, the schwa often occurs in different syllables. The reason is that English stress is highly variable, and the schwa is restricted to unstressed syllables. From the examples it is clear that the position of the schwa often varies in related words.