The topic of syllable stress in English is a difficult concept to teach, learn, or understand. Often it is an error that is not addressed at all. Why do teachers minimize it and learners avoid it? Why are researchers baffled by it? The rules to English syllable stress are unfathomable. Oh, there are rules, but when these rules are put together, there would be enough to write a one-thousand page book in very small font. Obviously a matter this complex is very difficult for everybody to comprehend and creates quite a cognitive load when we try to process stress rules that have been learned explicitly.
Researchers at the Max Planck Institute for Psycholinguistics have discovered that stress usually only affects the comprehension of a word if the quality of the vowel is also affected. What does this mean? I for one have witnessed numerous times in English and French classes how misplaced stress causes a second-language speaker to be misunderstood.
So what they are saying is, there is not much difference between
A. ON ly B. on LY
(The capital bolded letters indicate stress. The correct stress pattern is shown in A.)
The listener would understand the word said either way. The vowel sounds, in the example, are the same except that in column A the sound of ‘o’ is longer than the sound of ‘y’ and the reverse in column B. It should be fairly clear to most people what is being said in either instance.
However, consider some different examples:
|O ften||o FTEN|
|SE ve ral||se VE ral|
|a BI li ty||A bi li ty|
When the stress is misplaced on these words, it is more difficult for the listener to understand the word. Why? It’s the ‘destress’. Some vowel sounds, when not stressed, undergo a process that not only shortens the duration, but also changes the quality. So the stressed ‘O’ in ‘O ften’ is longer and has a different sound than the ‘o’ in o ften. Compare the sound of the first ‘e’ in ‘SE veral’ with ‘se VER al’. The word in column A sounds like the short ‘e’ as in ‘when’, where the first ‘e’ in column B sounds closer to the short ‘u’ as in ‘jump’ or the short ‘i’ sound as in ‘pick’. Notice how the sound of the ‘a’ in ‘ability’ changes when it is stressed and when it is not stressed. In column A the sound is reduced, but in column B it sounds like short ‘a’ as in ‘apple’.
The main point is that when a syllable containing a short vowel is not stressed, it becomes ‘destressed’ or reduced. The process of reducing changes the sound of the vowel which affects the listener’s comprehension.
The ‘destress’ situation has a great impact on a listener’s comprehension of a word because of its vowel quality changing effects. One very simple and effective way to overcome the complexity is to have students focus on practising the ‘destressed’ syllables rather than the stressed ones. You will find that learners sound more natural and, more importantly, are better understood if they have the ability to change the sound of short vowels when it should be reduced as it would in a native-English speaker’s pronunciation.
Which words do your students find stress-challenged?