Phonetic environment in the context of "Sound change"

In linguistics, vowel length is the perceived or actual duration of a vowel sound when pronounced. Vowels perceived as shorter are often called short vowels and those perceived as longer called long vowels.

On one hand, many languages do not distinguish vowel length phonemically, meaning that vowel length alone does not change the meanings of words. However, the amount of time a vowel is uttered can change based on factors such as the phonetic characteristics of the sounds around it: the phonetic environment. An example is that vowels tend to be pronounced longer before a voiced consonant and shorter before a voiceless consonant in the standard accents of American and British English.

The distinction between rhoticity and non-rhoticity is one of the most prominent ways in which varieties of the English language are classified. In rhotic accents, the sound of the historical English rhotic consonant, /r/, is preserved in all phonetic environments. In non-rhotic accents, speakers no longer pronounce /r/ in postvocalic environments: when it is immediately after a vowel and not followed by another vowel. For example, a rhotic English speaker pronounces the words hard and butter as /ˈhɑːrd/ and /ˈbʌtər/, but a non-rhotic speaker "drops" or "deletes" the /r/ sound and pronounces them as /ˈhɑːd/ and /ˈbʌtə/. When an r is at the end of a word but the next word begins with a vowel, as in the phrase "better apples," most non-rhotic speakers will preserve the /r/ in that position (the linking R), because it is followed by a vowel.

The rhotic dialects of English include most of those in Scotland, Ireland, the United States, and Canada. The non-rhotic dialects include most of those in England, Wales, Australia, New Zealand, and South Africa. Among certain speakers, like some in the northeastern coastal and southern United States, rhoticity is a sociolinguistic variable: postvocalic /r/ is deleted depending on an array of social factors, such as being more correlated in the 21st century with lower socioeconomic status, greater age, particular ethnic identities, and informal speaking contexts. These correlations have varied through the last two centuries, and in many cases speakers of traditionally non-rhotic American dialects are now rhotic or variably rhotic. Dialects of English that stably show variable rhoticity or semi-rhoticity also exist around the world, including many dialects of India, Pakistan, and the Caribbean.

In the sociolinguistics of the English language, /æ/ raising or short-a raising is a phenomenon by which the "short a" vowel /æ/ , the TRAP/BATH vowel (found in such words as lack and laugh), is pronounced with a raising of the tongue. In most American and many Canadian English accents, /æ/ raising is specifically /æ/ tensing: a combination of greater raising, fronting, lengthening, and gliding that occurs only in certain phonological environments or certain words. The most common context for tensing /æ/ throughout North American English, regardless of dialect, is when this vowel appears before a nasal consonant (thus, for example, commonly in pan, but rarely in pat).

The realization of this "tense" (as opposed to "lax") /æ/ includes variants such as [ɛə], [eə], [ɛː], etc., which can depend on the particular dialect or even speaker. One common realization is [ɛə], a transcription that will be used throughout this article as a generalized representation of the tensed pronunciation.