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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.
