Postnasal Voicing

Many of the world’s languages display a phonetic pattern whereby obstruents appear as voiced when following a nasal consonant. This article proposes a phonetic mechanism that favors postnasal voicing. The mechanism is based on two effects, which sometimes reinforce, and sometimes contradict each another. One effect is “nasal leak,” the leakage of air through a nearly closed velar port during the coarticulatory period between an oral and a nasal segment. The other is “velar pumping,” which arises from the vertical motion of a closed velum. The main purpose of the article is to test this proposal, in two ways. First, a computational simulation of vocal tract aerodynamics is used to show that, under a range of plausible assumptions, the mechanisms posited would indeed produce a substantial phonetic effect in the direction of postnasal voicing. Second, measurements were carried out of the productions of 5 native speakers of English producing stops in a controlled comparison context (postnasal / [ tam___ ] vs. / postoral [ ta ___p ]). The results indicate that postnasal voicing present as a quantitative effect even in a language whose phonology lacks a qualitative postnasal voicing process.