Edward Flemming

Phonetics, phonology. From MIT. Location: SAC 304

The role of distinctiveness constraints in phonology

Distinctiveness constraints favor maximization of the perceptual differences between contrasting sounds - less distinct contrasts incur more severe constraint violations. Perceptually indistinct contrasts are disfavored because they increase the likelihood of confusion on the part of listeners.

The preference for distinctive contrasts can be observed in the typology of segment inventories. For example, there is a crosslinguistic preference for front unrounded and back rounded vowels because these yield more distinct contrasts in second formant frequency than front rounded or back unrounded vowels. Distinctiveness constraints also give rise to positional neutralization effects where a contrast is neutralized in environments where it would not be sufficiently distinct. E.g. stop voicing contrasts are neutralized in final position where crucial Voice Onset Time cues are not available.

However, if distinctiveness constraints interacted freely with other phonological constraints, we would also expect to find positional enhancement as a counterpart to positional neutralization, that is we should find that measures are taken to increase the distinctiveness of contrasts precisely where they would otherwise be neutralized due to insufficient distinctiveness. I will argue that this phenomenon is not attested, drawing on evidence from asymmetries between the typologies of neutralizing consonant assimilation and vowel epenthesis, a potential enhancement for many consonant contrasts.

The non-existence of positional enhancement is accounted for by a model in which the basic role of distinctiveness constraints lies in deriving an inventory of contrasting segments which serves as the ‘alphabet’ from which underlying forms are constructed, much like a phoneme inventory. This is the locus of context-free enhancement effects. The second role of distinctiveness constraints is to operate like a filter on the outputs determined by the interaction of correspondence constraints and regular markedness constraints. If a contrast is insufficiently distinct it can only be neutralized (giving rise to positional neutralization), so distinctiveness constraints cannot condition epenthesis or other changes to improve distinctiveness.