American English Stress

The underlying pattern of English rhythm is that the stressed syllables of stressed words occur on relatively evenly spaced "beats." This concept is called the Rhythm Rule. This pattern is possible because words and sentences have three levels of stress:

  1. stressed
  2. unstressed
  3. secondarily stressed

Stressed syllables and words

Within words, a single stressed syllable is given emphasis by any combination of being pronounced louder, for more time, and/or at a different pitch than surrounding syllables. A stressed syllable of a word is mostly static and unchanging.

Stressed syllables
of words don't
usually change.
stressed syllable   stressed syllable
          
volunteer      inspiration
      

Sentence stress is more flexible than syllable stress. Which word is stressed can change to fit the speaker's intended meaning. A word is stressed by emphasizing its stressed syllable more than the stressed syllable of surrounding words.

Stressed words
of sentences are
very flexible.
stressed syllable
     
Are you coming? 
  
Or possibly:
stressed syllable
     
Are you coming? 
  
Or even:
stressed syllable
     
Are you coming? 
  

In short, the stressed syllable of a word rarely changes, but stressed words of a sentence are greatly flexible.

Unstressed syllables and words

Equally important to the rhythm of English is the reduction of unstressed syllables and unstressed words. Syllables and even entire words can be reduced by any combination of using a more neutral vowel sound (schwa), decreasing the length of the vowel sound, and omitting sounds (possibly entire syllables).

In both words and
sentences, unstressed
syllables often occur
next to stressed syllables.
unstressed syllable   unstressed syllables
             
volunteer      inspiration 
         
unstressed syllables
    
Are you coming? 
  

Secondarily stressed syllables and words

Secondarily stressed syllables create a beat of less prominence than a stressed syllable and are not reduced. Their primary purpose is in maintaining the rhythm of English. Secondarily stressed syllables are usually separated from stressed syllables by at least one unstressed syllable. Within sentences, words can also be given a secondary stress, either to highlight important information or even merely to maintain rhythm.

Secondarily stressed syllables
are usually separated
from stressed syllables by
at least one unstressed syllable.
secondary stress   secondary stress
             
volunteer        inspiration 
       
secondary stress
     
Are you coming?