Word Stress

This part was also taken from  "Sound Foundations, Learning and teaching pronunciation", Adrian Underhill, Macmillan, 2005.

I absolutely love that book. You should get it! It was written in a very simple and clear way.

Word Stress

"Word stress is the term used to describe the accent or emphasis given to a

particular syllable of a word, and it is a more or less invariable attribute of that

word when spoken in isolation. Words of more than one syllable contain both

stressed and unstressed syllables. Learners’ dictionaries indicate the stressed

syllable(s) for every multi-syllable word as if it were being spoken in isolation.

The stress symbol used by most dictionaries is /'/ just before the affected syllable,

eg/spə'sIfIk/.The location of this stress is as much a part of the pronunciation of a

word as are the phonemes themselves. Sounds and stress both contribute to the

acoustic identity of a word, so both need to be studied at the same time."

A practical definition of stress

"A stressed syllable is articulated with relatively more force than an unstressed

syllable. This is due to the extra pressure of air reaching the vocal cords, caused by

an increase in lung power. There are three distinguishable acoustic results. You may perceive syllables as stressed if, compared with their neighbours, they are

relatively:

1 louder;

2 longer;

3 different in pitch (usually higher but possibly lower).

To this we can add a fourth variable:

4 the sounds in a stressed syllable may be more clearly articulated, and in

particular the vowels may be ‘purer’.

As a result of this we can also add a fifth variable, which also provides a visual clue:

5 stressed syllables may be accompanied by larger jaw, lip and other facial

movements by the speaker.

These five variables are in fact all interrelated, because they are all ways of

increasing or decreasing the amount of energy in the articulation at any point.

They all concern the way that articulatory energy is distributed across the word.

In fact you can think of the stress pattern of a word as its energy profile."

Unstress in words

"Insofar as loudness, length and pitch correlate with stress, so absence of all three

can correlate with unstress.

Regarding the fourth variable, clarity and purity of articulation, it is worth saying

more about the changes that can result from unstressing the sound:

1 The consonants in an unstressed syllable may be more weakly or even

incompletely articulated.

2 The vowel in the syllable may sound less distinct. This loss of sharpness in

unstressed vowels is called reduction, and all vowel sounds can undergo greater

or lesser degrees of reduction. All monophthongs reduce towards the central

/ə/ sound, though /i: / often reduces to /I/ and /u: / often reduces to /ʊ/

Unstressed diphthongs become generally less distinct, often losing their two vowel

glide quality and merging into one composite ‘greyish’ monophthong."

Primary and secondary stress

"Longer words, especially when spoken in isolation, may have more than one

stressed syllable (eg popularity), in which case one of the stresses is given more

force than the other. The strongest is referred to as primary stress and the less

strong as secondary stress.

Both primary and secondary stress are in contrast to unstress. Secondary stress

can be realized acoustically by duration and loudness, and through clearer

articulation. It merely has less energy than its neighbouring primary stress.

However the pitch change quality of stress tends to occur as an attribute of

primary stress only."

Stress shift in words

"Sometimes words with secondary stress change their stress pattern in connected

speech, especially when followed by a word which is more strongly stressed." In those cases, we shift the main stress to the position of the secondary stress

 "Sound Foundations, Learning and teaching pronunciation", Adrian Underhill, Macmillan, 2005.