Schwa Lowering
What is schwa lowering?
We have seen elsewhere (Central Vowels) that one of the two central vowels of English frequently appears in unstressed syllables. This is the schwa vowel /ə/. We have also noted that this phoneme occupies a mid position, being articulated with the mouth open halfway between close-mid and open-mid (see Figures 9 and 10, Central Vowels). Now, consider the exact placement of this vowel in the following words.
appease /əˈpiz/
Pisa /ˈpizə/
Each of these words is a disyllable with /ə/ in the unstressed syllable. Do you notice any difference in the articulation of /ə/ between the two? Try saying the two words aloud, fairly deliberately and carefully. With careful attention, you should notice that the /ə/ vowel in the word appease is fairly close to the neutral mid position. However, in the word Pisa the vowel is slightly lowered towards the open-mid position. This shift to a lowered position is represented diagrammatically in Figure 2.
Figure 2. Lowered central schwa vowel.
In fact, this so-called schwa lowering occurs when the vowel /ə/ appears before a pause – in the case of Pisa the pause is the end of the word (if the word is spoken in isolation). We represent this phonetic variation symbolically as [ə↓]. The phonetic representation of /ə/ as it appears at the beginning of the word appease is written as [ə]. So, we can set out both the phonemic and phonetic transcriptions as follows.
phonemic transcription |
phonetic transcription |
|||
appease |
/əˈpiz/ |
→ |
[əˈpiz] |
|
Pisa |
/ˈpizə/ |
→ |
[ˈpizə↓] |
We conclude, therefore, that the phoneme /ə/ has at least two allophones: [ə] and [ə↓]. The allophone [ə↓] occurs before a pause, and the allophone [ə] occurs elsewhere. Remember that, these allophones do not appear in the same place at the same time. Table 1 summarizes how this phonetic feature affects the schwa vowel.
Table 1. Schwa allophone produced by lowering.
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