Speaker: Juliet Stanton (MIT) Title: Environmental shielding is contrast preservation Date: Monday, March 30th Time: 5-6:30 Place: 32D-831
The term “environmental shielding” refers to a class of processes where the phonetic realization of a nasal stop depends on its vocalic context. In Kaiwá (Tupí; Bridgeman 1961), for example, plain nasal stops are realized as prenasalized stops before oral vowels (i.e. /ma/ > [mba]) but as nasal stops before nasal vowels (i.e. /mã/ > [mã]). Herbert (1986:199) claims that the purpose of shielding is to protect a contrast between oral and nasal vowels. If Kaiwá /ma/ were realized as [ma], without the intervening [b], [a] would likely carry some degree of perseveratory nasal coarticulation and be less distinct from its nasal counterpart /ã/ as a result.
This paper provides several arguments that Herbert’s position is correct – that environmental shielding is contrast preservation, and that any successful analysis of shielding must make explicit reference to contrast. Results from a survey of over 150 languages reveal a stark asymmetry in the typology of shielding: all languages that exhibit shielding also license a contrast in vocalic nasality (see also Herbert 1986:219). In addition, further asymmetries within the typology mirror known cross-linguistic asymmetries in the direction and extent of nasal coarticulation. I propose an analysis referencing auditory factors that predicts these asymmetries, and show that its broader predictions, though not yet fully investigated, appear to be on the right track.