Learning new sounds of speech: reallocation of neural substrates

Individual differences in the acquisition of second language phonology

“…Linguistic experience did not predict any of the pre-test, post-test, or training measures, suggesting that such individual differences may not be explained by differences in language background. This variability is consistent with the results of previous studies on non-native speech sound learning (Bradlow et al, 1997;Golestani & Zatorre, 2004;Fig. 9.…”

“…Alternatively, it is possible that 'faster' phonetic learners are precisely those who are able to stop hearing certain novel speech sounds in a speech-specific manner, which likely depends in part on how sounds are to be articulated (Liberman, Cooper, Shankweiler, & Studdert-Kennedy, 1967;Liberman & Mattingly, 1985), and who instead are better able to focus on the sounds themselves, and thereby to hear the sounds in a more bottom-up, stimulus-driven mode (i.e., to attend more to the physical/acoustic characteristics of the auditory input). We have functional brain imaging data suggesting that the successful learning of a non-native phonetic contrast results in the recruitment of the same areas that are involved during the processing of native contrasts (Golestani & Zatorre, 2004). These results would support the former rather than the latter of the two above hypotheses, or at least they can help to exclude the latter, since they suggest that the learning of non-native speech sounds results in the recruitment of a speech-specific network.…”

“…The training procedure was the same as that used in this study, apart from the fact that it was much longer. We found that only half of the participants improved over the course of this much longer training (Golestani & Zatorre, 2004). Further, in two, related anatomical magnetic resonance imaging (aMRI) studies, it was found that people who are faster at learning to hear the dental-retroflex contrast have a greater left > right asymmetry in parietal lobe white matter volumes (Golestani et al, 2002), as well greater white matter volumes of left Heschl's gyrus, a part of the brain which includes primary auditory cortex (Golestani et al, 2007) than do slower learners.…”

“…Training was discontinued either once a participant achieved criterion on this last contrast, or once they had completed a maximum of 200 trials (10 blocks), and lasted twenty to thirty minutes per stimulus type. This is a short training session compared to the amount of training that is typically administered in other phonetic training studies, where it ranges from 1 to 18 training sessions lasting up to an hour each (Carney, Widin, & Viemeister, 1977;Golestani & Zatorre, 2004;Pisoni, Aslin, Perey, & Hennessy, 1982;Strange & Dittmann, 1984).…”

“…There is evidence, however, for considerable variability across individuals in the learning of speech sounds that involve rapid spectral change, in particular ones that contrast place of articulation, such as the r/l contrast for native Japanese listeners, or the dental-retroflex one for native English speakers. Specifically, even among individuals with similar language backgrounds, some are able to hear these non-native sounds in adulthood, or to learn them quickly with limited training, while for others, learning to hear these sounds is more slow and effortful (Bradlow, Pisoni, Akahane-Yamada, & Tohkura, 1997;Golestani & Zatorre, 2004;Polka, 1991;Pruitt, Strange, Polka, & Aguilar, 1990).…”