In English
there are three degrees of word stress: stressed
syllables (primary stress), half-stressed
syllables (secondary stress) and weak or unstressed syllables.
A large group of polysyllabic simple words has both the primary and the secondary stresses: `conver`sation, `organi`zation.
There are several large groups of words in English with two equally strong stresses. The use of the second stress is caused by the semantic significance of both equally stressed elements of the word: rewrite, fourteen.
Sentence stress. In a sentence or an intonation group some of the words are of greater importance than the others. This mostly depends on the situation or context. Words which provide most of the information are brought out in our speech by means of sentence stress.
Thus sentence stress is a special prominence, given to one or more words according to their relative importance in a sentence.
There are three types of sentence stress:
1) Normal stress affects content words which convey the necessary information to the listener. I like oranges.
2) Logical stress. By shifting the position of the last stress we can change the place of the nucleus of the communicative center. My sister hates yellow jeans.
The type of sentence stress which gives special prominence to a new element in a sentence or an intonation group is called logical stress. The word which is singled out by the logical stress is the most important in the sentence.
3) Emphatic stress. Any word in sentence, including form words, personal and possessive pronouns, auxiliary and modal verbs may be logically stressed. Most utterances express not only the speaker's thoughts, but also feelings and attitudes to reality and to the sentence. Both normal and logical stresses can be unemphatic and emphatic. Emphatic stress increases the effort of expression. The High Fall of Rise-Fall are usually used in this case. You are so nice!