One or more syllables of a polysyllabic word have greater prominence than the others. Such syllables are said to be accented or stressed.
In English any or all of four factors - loudness (force), pitch, sound quantity (length), sound quality may render a syllable more prominent than the others. In similar phonetic contexts a vowel is perceived as a more prominent one if it is louder, longer and more distinct than the unstressed one. Even vowels of full formation in the unstressed position are not so distinct as their stressed counterparts. The pitch component of word stress manifests itself in the fact that the stressed syllable is always that on which there is a potential change of pitch in the phrase though the stressed syllable is not necessarily higher than the unstressed one. cf compound (n) ('kDmpaund] and compound (v) (k;)m'paund).
Vowels of unstressed syllables are definitely not so long and tend to be reduced in the unstressed position. The effect of word stress in Russian is achieved by the same factors, the main difference being connected with the quantity and the quality of the vowel sound. Though English vowels are shorter in the unstressed position the difference between historically long and historically short vowels remains quite distinct. In Russian variations of vowel length are only due to the degree of stress. Russian vowels are regularly longer in stressed syllables than in unstressed ones. As to quality all Russian vowels are qualitatively reduced in the unstressed position, eg KOMap, nOMU- gop.
Our treatment of word stress as of any other component of pronunciation is based on its two linguistic functions, constitutive and distinctive.
Word stress arranges syllables in words thus fulfilling the constitutive function. Its distinctive function can be traced in the oppositions of words consisting of the same morphemes the meaning of which is differentiated by word stress, eg object (n) ['ob<tlkt) - object (v) [;)b 1 <tekt); lrygHClR - "I.ygHciR.