I’ve greatly appreciated your synthesis (thanks to...

2012-01-24T11:57:11.736-08:00

I’ve greatly appreciated your synthesis (thanks to Anne-Lise Giraud for linking me to your blog). One point I find especially appealing is that your computational model solves the difference in timing between internal and external feedback monitoring. I’ve proposed a solution to a somewhat similar problem, the one of differences in spatial representation of speech sounds between the auditory and motor systems. This problem originates from the fact that frontward movements in the vocal tract have opposite acoustic consequences for vowels and consonants. Compare a vowel sequence such as /iu/ (‘you’) with a consonant sequence such as /bʌg/ (‘bug’). Both are produced with a backward motor change, but they have opposite acoustic effects: a downward frequency change for /iu/ vs. upward change for /bʌg/. As a consequence, the perception of motor changes is distorted in an acoustic-auditory representation. To interpret a downward frequency change as a backward movement will be right for vowels but false for consonants. However, this problem can be solved if there is an inversion of the perceptual representation at some further processing stage. Evidence in support of this conjecture has been gained with behavioral data in a series of experiments with French-like /i,y,u/ and /b,d,g/ synthetic sounds [1,2]. We’ve found that perceptual boundaries between the vowels did not match those between the stops in an acoustic representation. However, there was a close match between the vowel and stop boundaries after a rotation of the acoustic representation. This shows that there is a mathematical solution (the rotation of the acoustic space) to the lack of common representation of the spatial relationships between vowels and of those between consonants. But it remains to be proven that this solution is indeed used by the brain. We are now currently seeking ways to test this hypothesis.

willy.serniclaes@ulb.ac.be
http://lpp.psycho.univ-paris5.fr/person.php?name=WillyS

[1] first publication of data with adults:
Serniclaes, W. & Salinas, J. (2011). Perception of vowels and consonants: From acoustic diversity to cognitive isotropy. Faits de Langue, 37, 207-224.

[2] under way: a second publication with both adults and children data and also psychoacoustic data (sinewaves analogues of speech sounds, first heard non speech whistles, then as speech sounds using the same paradigm as e.g. Dufor et al., 2007; 2009).

Dufor, O., Serniclaes, W., Sprenger-Charolles, L., & Démonet, J.-F. (2009). Left pre-motor cortex and allophonic speech perception in dyslexia: A PET study. NeuroImage, 46, 241–248.

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I’ve greatly appreciated your synthesis (thanks to...