This is sometimes so short that non-native speakers, perhaps not accustomed to it, fail to recognize it at all.

Many students, for example, don't recognize the normal pronunciation "there are" for the words there are which occur at the beginning of so many English sentences.

Furthermore, they encounter a similar problem with unstressed syllables which are part of a longer word.

For instance, think of the word cotton, which is spelt c-o-t-t-o-n, I'll repeat that, c-o-t-t-o-n. Each letter is the same size, no difference is made between the fist syllable cot- and the second syllable -ton.

In speech, however, the first syllable is stressed, the second is unstressed. The word is not pronounced cot-ton, but cot-n.

The same is true for the word carbon, spelt c-a-r-b-o-n, it's not pronounced car-bon, but car-bn.

But I want now to come on to the second main problem, the difficulty of remembering what's been said. Again, the problem here is much less difficult in the written rather than the spoken form.

Words on a page are permanently fixed in space. They don't disappear like words that are spoken. They remain in front you. You can choose your own speed to read them, whereas in listening, you've got to follow the speed of the speaker.