section_path: Phonology/Stress, rhythm and intonation
section_name: Stress, rhythm and intonation
paragraph_text: Stress, rhythm and intonation
  
  Stress plays an important role in English. Certain syllables are stressed, while others are unstressed. Stress is a combination of duration, intensity, vowel quality, and sometimes changes in pitch. Stressed syllables are pronounced longer and louder than unstressed syllables, and vowels in unstressed syllables are frequently reduced while vowels in stressed syllables are not. Some words, primarily short function words but also some modal verbs such as can, have weak and strong forms depending on whether they occur in stressed or non-stressed position within a sentence.
  
  Stress in English is phonemic, and some pairs of words are distinguished by stress. For instance, the word contract is stressed on the first syllable (/ ˈ k ɒ n t r æ k t / KON -trakt) when used as a noun, but on the last syllable (/ k ə n ˈ t r æ k t / kən- TRAKT) for most meanings (for example, "reduce in size") when used as a verb. Here stress is connected to vowel reduction: in the noun "contract" the first syllable is stressed and has the unreduced vowel /ɒ/, but in the verb "contract" the first syllable is unstressed and its vowel is reduced to /ə/. Stress is also used to distinguish between words and phrases, so that a compound word receives a single stress unit, but the corresponding phrase has two: e.g. a burnout (/ ˈ b ɜːr n aʊ t /) versus to burn out (/ ˈ b ɜːr n ˈ aʊ t /), and a hotdog (/ ˈ h ɒ t d ɒ ɡ /) versus a hot dog (/ ˈ h ɒ t ˈ d ɒ ɡ /).
  
  In terms of rhythm, English is generally described as a stress-timed language, meaning that the amount of time between stressed syllables tends to be equal. Stressed syllables are pronounced longer, but unstressed syllables (syllables between stresses) are shortened. Vowels in unstressed syllables are shortened as well, and vowel shortening causes changes in vowel quality: vowel reduction.