Vowel reduction in English

In English, vowel reduction is the centralization and weakening of an unstressed vowel, such as the characteristic change of many vowels at the ends of words to schwa. Stressed vowels cannot be reduced.

Reduced vowels

Schwa is the most common reduced vowel in English, and orthographically it may be denoted by any of the vowel letters:

* The "a" in "about".
* The "e" in "synthesis".
* The "o" in "harmony".
* The "u" in "medium".

The following are also schwas, except in dialects that have two distinct reduced vowels (see below).
* The "i" in "decimal".
* The "y" in "syringe".

Whereas the sound represented by the "er" in "water" is a schwa in non-rhotic accents like Received Pronunciation, in rhotic dialects like most of North American English, "er" designates an r-colored schwa, IPA| [ɚ] , which is pronounced like schwa, except the tongue is pulled back in the mouth and "bunched up".

In some dialects of English there is a distinction between two vowel heights of reduced vowels, schwa and "barred i," the near-close central unrounded vowel IPA|/ɪ̈/ (or equivalently IPA|/ɨ̞/), sometimes called "schwi". In the British phonetic tradition, this is written IPA|/ɪ/, and in the American tradition IPA|/ɨ/. (The OED has recently ["c." 2005] converted to IPA|/ɪ̵/.) An example of a minimal pair contrasting schwa and barred i:

* The "e" in "roses" is a barred i
* The "a" in "Rosa’s" is a schwa(See Phonological history of English high front vowels.)

Many dialects also retain rounding in reduced vowels, with IPA|/uː/ and IPA|/ʊ/ reducing to IPA| [ʊ̈] (or equivalently IPA|/ʉ̞/; IPA|/ʊ̵/ in OED transcription), and IPA|/oʊ/ reducing to IPA|/ɵ/.

The other sounds that can serve as the peak of reduced syllables are the syllabic consonants. The consonants that can be syllabic in English are the nasals IPA|/m/, IPA|/n/, IPA|/ŋ/, and IPA|/l/ (actually a dark l). For example:

* The "m" in "prism" is sometimes a syllabic IPA|/m/.
* The "on" in "button" is a syllabic IPA|/n/ in dialects that pronounce 't' as a glottal stop.
* The word "and" in the phrase "lock and key" in more rapid speech is sometimes pronounced as a syllabic IPA|/ŋ/.
* The "le" in "cycle" and "bottle" is a syllablic IPA|/l/.

These reduced vowels contrast in the word "parallelepipedal" IPAEng|ˌpærəlɛlᵻˈpɪpɛdl̩, and in some dialects "idler" IPA|/ˈaɪdl̩ɚ/.

The vowels and diphthongs IPA|/ɔː/, IPA|/aʊ/, and IPA|/ɔɪ/ are never reduced, and all vowels may occur in unstressed position without reduction, especially in compound words. (These are often transcribed in dictionaries as having secondary stress, but that is a convention for unreduced vowels that occur after the primary stress. See secondary stress.)

::note label|reducedlength|a|a Sometimes with reduced length, but nevertheless with unreduced vowel quality

Nonetheless, it is true that some vowels, such as IPA|/ɪ/ and IPA|/ʌ/, reduce quite readily, so that there are not many English words which have them in unstressed positions.

Alternation

Some English words alternate between having full but unstressed vowels and reduced vowels, depending on context. For example, "the" is typically IPA|/ðiː/ before a vowel-initial word ("the apple") but IPA|/ðə/ before a consonant-initial word ("the pear"), though this distinction is being lost in the United States.Ladefoged, "A Course in Phonetics"] Similarly with "to": "to America" IPA|/tuː/ vs. "to Britain" IPA|/tə/. Most words, however, alternate depending on how much emphasis they are accorded. Some of these are:

*"can": IPA|/kæn/, but also "I can go" IPA|/ˈaɪ kŋ ɡoʊ/,
*"and": IPA|/ænd/, but also "you and me" IPA|/ˌjuː ən ˈmiː/,
*"he": IPA|/hiː/, but also "will he go?" IPA|/ˈwɪl ɪ goʊ/,and so on with "a, at, would, that, has, etc."

There are also a number of English verb-adjective pairs that are distinguished solely by vowel reduction. For example, "separate" as a verb (as in 'what separates nation from nation') has a full final vowel, IPA|/ˈsɛpəreɪt/, whereas the corresponding adjective (as in 'they sleep in separate rooms') has a reduced vowel: IPA|/ˈsɛpərət/. [OED]

Notes

See also

*Schwa
*Tenseness
*Vowel reduction
*Vowel reduction in Russian