Stress-timed and syllable-timed rhythms

In English the syllable can also, potentially, be a unit of rhythm but stress-timed rhythm is more typical of English, as well as Russian, German and Dutch. Other languages, like French, Spanish, Italian, Greek, Hindi, Indonesian and Yoroba have syllable-timed rhythm. The term suggests that syllables come at equal intervals, taking relatively the same length of time. For example, in Japanese the expression tokoro-dokoro {here and there) sounds as if each syllable takes an equal amount of time, rather like to-ko-ro-do-ko-ro.

Stress-timed languages like English, Russian and Arabic, German, Swedish, Brazilian Portugese and conversational Thai seem to have stressed syllables coming at regular intervals. Do speakers of these languages actually aim at stress groups isochrony? And is it absolute or just perceptual isochrony?

These are not simple questions to answer. Actually there is a tendency for stresses to recur regularly in most languages. The average ratio between stressed and unstressed syllables in languages forms a scale along which different languages can be situated. A continuum was proposed by which we can order languages according to differences in syllable structure, vowel reduction, and the phonetic influence of stress. Thus both English and Japanese are stress-timed, but at the opposite ends of the continuum if we consider how they use syllable rhythm and stress-patterning: Japanese > French > Spanish > Greek > Portugese > English.

Scholars have attempted to find an explanation why languages like French, Japanese and Spanish are categorized differently from languages like English, Russian and German.

First, there is considerable variation in syllable length in English, as well as many different kinds of syllables. In contrast with English, Japanese usually has V and CV syllables. It was also found that open syllables make up a minority of the total in English, compared with a majority in Spanish, for instance {Dauer 1983).

Secondly, English uses a restricted set of vowels in unstressed syllables, typically [э] or [i]. Such reduced vowels also appear in unstressed function words and morphological endings which carry little semantic information, and thus appear subjectively shorter than full vowels in stressed syllables. In Spanish 90% of the unstressed CV syllables have longer peripheral vowels.

Third, most stress-timed languages have a word stress, often a somewhat unpredictable free stress, realized by changes in length, pitch, loudness and quality. Stressed syllables last about 200 to 350 milliseconds, transmitting information on 1 to 6 phonemes; unstressed syllables only last 100 milliseconds or less. English stressed syllables are typically 1.5 times longer than unstressed syllables, while in Spanish they are about 1.3 times longer. The differential effects are especially noticeable in utterance-open medial open syllables, where Spanish stressed syllables are only 1.1 times longer than unstressed syllables, while English stressed syllables are 1.6 times as long as unstressed syllables {Dauer 1983: 58).

This makes English stressed syllables even more prominent than unstressed syllables, giving a clearly discernable beat to which listeners are sensitive. The stress patterns provide information about the phonological identity of a word. In English it is often the root of the word that is stressed, and it is a crucial factor in successfully searching the lexicon for the right word {Cutler 1989, Kess 1992).

The overall conclusion is that "the rhythmic differences we feel to exist between languages such as English and Spanish are more a result of phonological, phonetic, lexical and syntactical facts about the language than any attempt on the part of the speaker to equalize interstress and intersyllable intervals." It is ultimately a product of the entire linguistic system {Dauer 1983: 55).

The typology of stress patterns in two language families, Germanic languages and Romance languages, could be completed by the statement that in Germanic languages (Dutch, German, Danish, Swedish, English) the enclitic tendency prevails: in a stress group unstressed syllables (clitics) are grouped with a preceding stressed syllable. In Romance languages (French, Italian, Spanish, Romanian, except perhaps European Portug­ese) the proclitic tendency is more obvious: unstressed syllables are grouped with a following stressed syllables. D. Hirst and A. Di Cristo proposed to call them "left-headed" languages with the foot structures SssSssSss and "right-headed" languages with the foot structures ssSsssSssS {Hirst and Di Cristo 1998).

To sum up: the typology of stress patterns in different languages is based on the very substance of which both stressed and unstressed syllables are made: vowels and consonants are grouped according to the rules of the language phonology and phonotactics. The isochrony of English stress has proved to be perceptual: within a certain range of stress group length (200-600 ms) stresses sound regular and of equal length to the native speakers of English. The enclitic tendency is typical of all Germanic languages.

Дата добавления: 2014-01-11