* "[O]ne of the functions of phonetic stress is to make words understandable. This kind of stress, known as word-level stress, is actually part of a word's pronunciation. It may also serve to differentiate words that are similar. For example, We're going to record a record, the two similar words are stressed differently so that the first record is stressed on the second syllable (vowel reduction in the first syllable also assists in helping us to assign stress to the second syllable), whereas the second record is stressed on the first syllable (with vowel reduction in the second syllable). All words of more than one syllable have a prominent or stressed syllable. If we pronounce a word with appropriate stress, people will understand us; if we use the wrong stress placement, we run the risk of being misunderstood.

"Phrase or sentence stress is tied to meaning, and this is the second function of stress. As we focus a camera on some item of interest, phonetic stress helps us focus our listener's attention on what is most important in our message."
(Harold T. Edwards, Applied Phonetics: The Sounds of American English, 3rd ed. Thomson, 2003)

* "Stresses tend to recur at regular intervals. But the sound pattern of English does not make it an overriding necessity to adjust the lengths of syllables so as to enforce complete regularity. The interval between stresses is affected by the number of syllables within the stress group, by the number and type of vowels and consonants within each syllable, and by other factors such as the variations in emphasis that are given to each word."
(Peter Ladefoged and Keith Johnson, A Course in Phonetics, 6th ed. Wadsworth, 2011)

* Stress With Content Words and Function Words
"[T]he words most likely to receive sentence stress are those termed content words (also called 'lexical words'), namely nouns, adjectives, adverbs,