Native speech plasticity in the German-English late bilingual Stefanie Graf: A longitudinal study over four decades

Abstract

The purpose of this study was to expose the trajectory of native speech plasticity in the context of late bilingualism through analysis of spontaneous speech of Stefanie Graf (SG) over four decades.With regard to segmental variables, results showed a significant lowering of F2 in /l/, suggesting darkening of the German lateral under the influence of English as a second language (L2). F2 significantly increased in /i/, indicating a more front pronunciation, as predicted due to English L2 acquisition. There was also a significant decrease in F1 of /l/, as well as of /i/, but a significant increase in the F1 frequency of /a/, suggesting widening of the vertical vowel space, potentially due to increasing age. Regarding prosody, there was a significant decrease in pitch level and narrowing of pitch span over time, as expected with increasing age, and surprisingly an increase in average maximum f0 over time, possibly as a result of English L2 acquisition of prosody.These findings suggest that native speech remains plastic post adolescence throughout adulthood, here proposed to be evidenced through a result of acquisition of L2 counterparts in late bilingualism, and that such changes are intertwined with natural biological speech developments over the lifespan.