"Economic and cultural globalization has turned the learning of foreign languages into a socioeconomic need. For that reason, the learning of at least one foreign language is a compulsory subject in the academic curriculums of most countries in Europe and around the world. One of the greatest difficulties for the learners of second languages (L2) is to accurately produce and perceive the speech sounds (phonemes) of the new language and, despite educational efforts of foreign language programs, few individuals manage to achieve high proficiency levels in these skills. The present study aims to investigate the functional and anatomical brain correlates of variability in the degree of success in the learning of the L2 phonemes.Our research question will be addressed by investigating (i) functional, (ii) morphological, and (iii) functional connectivity differences between good and poor perceivers of the L2 by means of magnetic resonance imaging (MRI). Individual differences in the learning of the L2 sounds will investigate all the levels of the phonological processing hierarchy (i.e., processes that cover auditory-sensory analysis, speech analysis, and attention) involved in producing and perceiving native phonemes.The results of this research are not only relevant because they will enhance our knowledge about how the brain processes and learns languages but also because they have the potential to help in the development of efficient language teaching programs."