Two Schwas In English

The schwa is classified as a mid central vowel, but English has two. The schwa in word-final  position is significantly different from the schwa in other positions. The word-final schwa has a relatively consistent vowel quality, but the word-internal schwa is higher and varies in backness and lip position.

The word-initial schwa in words such as about, against and ago patterns similarly to the word-medial schwa of entrance, general and summary. The word-final schwa corresponds to an orthographic a. On the other hand, the schwa in other positions can correspond to a number of letters. For example, it is an e in seven, an o in apron and a u in campus.

In an experiment by Edward Flemming (2007), nine female speakers of American English pronounced words with word-final schwas such as Rosa, sofa and umbrella and words with word-medial schwas such as probable, suggest and today. The medial schwas were high vowels, but the word-final schwas were central. The word-final schwas varied little in vowel quality, but the other schwas varied signficantly.

Unlike word-final schwas, word medial schwas are very short. To realize the vowel quality of the medial schwa, it is necessary to move from the articulatory position of the previous segment to the vowel target and then to the position for the following segment. In positions with very short vowel duration, vowels are likely to be strongly assimilated to surrounding segments. Word-medial schwas occur between two segments, but word-final schwas do not.

The English variable schwa results from the neutralization of all vowel qualities. However, the mid central schwa found in word-final position contrasts with unstressed [i] and [oʊ]. Compare the schwa of data with the vowels of city and motto.

English has two schwas. One is a word-final schwa and the other a variable schwa, which occurs word-internally. The word-final schwa is mid central and the variable schwa is high. The variable schwa has a shorter duration than the word-final one. Though word-internal and word-final schwas are transcribed with the same phonetic symbol, they are in fact different.