Other vowel features

Glide shortening in diphthongs (monophthongization)

The shortening of the offglides of diphthongs in words of the OIL class and of the PRIZE and PRICE classes (especially in the former) is one of the most noticeable features of SAmE. Words like oil are pronounced  in older and rural varieties of SAmE, while words in the PRIZE class typically have [a:ε ~a:ə ~a:] as stressed vowels. Although the history of glide shortening in the oil class is unclear, the shortening of offglides in PRIZE/PRICE classes (and in many cases the loss of the glide altogether) began during the last quarter of the 19^th century and expanded rapidly thereafter. By the middle of the 20^th century, glide-shortened and monophthongal variants of the PRIZE/PRICE classes were prevalent throughout most of the South, especially in voiced environments.

Glide shortening (or monophthongization) has always been constrained both phonologically and socially, however. A following r or l has always been the phonological environment that favors monophthongs the most, with following nasals and other voiced obstruents also quite favorable. Before voiceless obstruents, monophthongs have always been less common and more restricted both regionally and socially. Although in voiceless environments [a:ε ~a:ə ~a:] occurs throughout the South to some extent and even among African Americans sometimes, these realizations are most common in the Southern Appalachians and contiguous areas and in a broad area of Texas running west of Fort Worth through Lubbock. Likewise, monophthongs in the PRICE class are also far more common among whites than blacks. In spite of its widespread geographic and social provenance, however, glide shortening in both the PRIZE and PRICE classes, like the PEN/PIN merger, is receding in the largest cities of the urban South. Increasingly, young Southerners in metropolises like Dallas, Houston, and Atlanta have full diphthongs in all environments, although monophthongs still frequently appear before l and r. In these same areas, full offglides are becoming the norm in pre-l environments for vowels in the oil class as well.