The acoustic–perceptual salience of nasal place contrasts

This study examined the perception of the typologically frequent /m/-/n/ contrast and the less common /n/-/ŋ/ contrast in syllable-onset position. In an acoustic study of [ma], [na], and [ŋa] tokens as spoken by three native speakers of Filipino (Experiment 1), both static (F2 and F3 values measured at the nasal–vowel juncture) and dynamic (rms energy change from murmur to vowel onset) measures showed that [na] tokens are more similar to [ŋa] than to [ma]. To test whether the acoustic similarity led to corresponding perceptual effects, native English and Filipino listeners were presented Filipino [ma]-[na] and [na]-[ŋa] pairs in a discrimination test (Experiment 2). English listeners showed a non-native effect, accurately discriminating the [ma]-[na] distinction while performing at chance on [na]-[ŋa]. Interestingly, Filipino listeners showed the same pattern of performance, albeit at a more moderate level. The performance of Filipino listeners in Experiment 2 was interpreted as originating from the acoustic similarity between /na/ and /ŋa/. To draw out the effects of the varying perceptual salience of the two contrasts, in Experiments 3 and 4 Filipino listeners were presented with the same contrasts (with the addition of [ma]-[ŋa] in Experiment 4) for discrimination in three listening conditions: no additive noise, 0 and −5 dB SNR. Listeners’ discriminations of the [ma]-[na] and [ma]-[ŋa] contrasts remained near ceiling levels across the three conditions, while performance on [na]-[ŋa] fell to near chance in the noisiest condition. Taken together, these results are suggestive of a role for acoustic–perceptual salience in the distribution of nasal place contrasts in the world's languages, reflecting acoustically robust and perceptually distinct contrasts over those that are acoustically similar and perceptually confusable.