Vowel Reduction - Weakening of Vowels

Weakening of Vowels

Phonetic reduction most often involves a centralization of the vowel, that is, a reduction in the amount of movement of the tongue in pronouncing the vowel, as with the characteristic change of many unstressed vowels at the ends of English words to something approaching schwa. A well-researched type of reduction is that of the neutralization of acoustic distinctions in unstressed vowels, which occurs in many languages. The most common reduced vowel is schwa.

Whereas full vowels are distinguished by height, backness, and roundness, according to Bolinger (1989), reduced unstressed vowels are largely unconcerned with height or roundness. English /ə/, for example, may range phonetically from mid to to open ; English /ɨ/ ranges from close, to open-mid . The primary distinction is that /ɨ/ is further front than /ə/, contrasted in the numerous English words ending in unstressed -ia. That is, the jaw, which to a large extent controls vowel height, tends to be relaxed when pronouncing reduced vowels. Similarly, English /ɵ/ ranges through and ; although it may be labialized to varying degrees, the lips are relaxed in comparison to /uː/, /ou/, or /ɔː/. The primary distinction in words like folio is again one of backness. However, the backness distinction is not as great as that of full vowels; reduced vowels are also centralized, and are sometimes referred to by that term. They may also be called obscure, as there is no one-to-one correspondence between full and reduced vowels. (Bolinger 1989:347)

Centralisation isn't the only form of reduction, however. Many Germanic languages, in their early stages, reduced the number of vowels that could occur in unstressed syllables, without (or before) clearly showing centralisation. Proto-Germanic and its early descendant Gothic still allowed more or less the full complement of vowels and diphthongs to appear in unstressed syllables, except notably short /e/, which merged with /i/. In early Old High German and Old Saxon, this had been reduced to five vowels (i, e, a, o, u, some with length distinction), later reduced further to just three short vowels (i/e, a, o/u). In Old Norse, likewise, only three vowels were written in unstressed syllables: a, i and u (their exact phonetic quality is unknown). Old English, meanwhile, distinguished only e, a, and u (or o). Catalan, a Romance language, also shows reduction, but in differing degrees depending on dialect. The Valencian dialect reduces the number of possible vowels from seven to five in unstressed environments, merging into and into . The central Catalan dialect goes even further, distinguishing only, and or, with and becoming and and merging into . In Italian, the vowels noted e and o in spelling are pronounced and in unstressed syllables.

Sound duration is a common factor in reduction: In fast speech, vowels are reduced due to physical limitations of the articulatory organs, e.g., the tongue cannot move to a prototypical position fast or completely enough to produce a full-quality vowel. Compare: clipping (phonetics). Different languages have different types of vowel reduction, and this is one of the difficulties in language acquisition; see, e.g., "Non-native pronunciations of English" and "Anglophone pronunciation of foreign languages". Vowel reduction of second language speakers is a separate study.

Stress-related vowel reduction is a principal factor in the development of Indo-European ablaut, as well as other changes reconstructed by historical linguistics.

Such vowel reduction is one of the sources of distinction between a spoken language and its written counterpart. Vernacular and formal speech often have different levels of vowel reduction, and so the term "vowel reduction" is also applied to differences in a language variety with respect to, e.g., the language standard. In some cases phonetic vowel reduction may contribute to phonemic (phonological) reduction, which means merger of phonemes, induced by indistinguishable pronunciation.

Some languages, such as Finnish, Hindi, and classical Spanish, are claimed to lack vowel reduction. Such languages are often called syllable-timed languages. At the other end of the spectrum, Mexican Spanish is characterized by the reduction or loss of the unstressed vowels, mainly when they are in contact with the sound /s/. It can be the case that the words pesos, pesas, and peces are pronounced the same: . In the same way, Slovene has a stressed reduced vowel: /e/ appears as schwa in some reducing environments (such as /er/ when no other vowel is adjacent), even when the syllable is stressed.