plain (adj.)

One of the features of sound set up by Jakobson and Halle in their DISTINCTIVE FEATURE theory of PHONOLOGY, to handle variations in MANNER OF ARTICULATION, its opposite being FLAT or SHARP, depending on the contrast involved. ‘Plain’ is defined articulatorily and ACOUSTICALLY: in contrast to flat, it refers to sounds involving a relatively wide mouth opening, and a relatively strong high-frequency component of the sound spectrum, as in sounds lacking lip-ROUNDING; in contrast to sharp, it refers to sounds lacking any PALATALIZATION feature.