REDUCTION

The nature of reduction in English
For language teaching, J.C. Catford is the phonetician who worked most helpfully on vowel reduction. He noted (Catford, 1985) that there are two different kinds of schwa:

•   a minimal vowel-type sound, as in comma,
  
•   an open transition, as in today.
  The first of these will be familiar to you. The second, the idea of an open transition, was an insight which enables students to improve their pronunciation quickly and easily. As mentioned earlier, we have found that asking students to stutter is the best way into producing schwa as an open transition.
  Catford identified three differences between open transitions and full vowels. They differ in their duration, in the cross-sectional area of the channel (the extent to which the vocal tract gets opened), and in their phonation.
  He quotes figures showing that:
  

1. On average, open transitions are completed in only a quarter of the time it takes to
   say a vowel.
   
2. In his speech, the channel area for the open transition in cop apart was just 20 mm2
   while that for the vowels in copper part and cop up, Art were both over 200 mm2.
   
3. Open transitions may be fully voiced, partially voiced or totally voiceless (voiceless,
   for example in the to of He went to Trafalgar Square), while vowels are virtually always voiced.
   

So, when watching yourself making open transitions, notice,

1. how quick they are,
   
2. how little movement they involve, and
   
3. how their voicing depends on their context.
   

Once students understand how minimal an open transition should be, they are well equipped to produce the whole range of schwa, schwi and schwu.
They also understand how native speakers distinguish sentences such as My shoe’s dirty and My shoes are dirty, and can hear the difference that makes the difference even when listening to fast speech.
A quarter to two is a powerful example because it containts two succesive open transitions. It also demonstrates that there need be no consciously produced vowel sound at all. In fact, in this example, the vocal folds don’t vibrate; all that we hear is the release of the /t/’s, so one could reasonably say that there is no vowel being produced at all. An offer for free and nine and a ninth are similarly powerful phrases.
Teaching Pronunciation Differently is a TESOL EVO session.
For information and materials on teaching pronunciation, go to www.pronunciationscience.com