Vocal Learning in Adulthood: Investigating the mechanisms of vocal imitation and the effects of training and expertise.

We are genetically programmed to acquire spoken language from our environment, and infants can master native pronunciation in multiple languages without explicit tuition. However, in adolescence and adulthood we have a limited capacity to achieve accurate pronunciation of unfamiliar languages, and even highly competent users of a language learned in adulthood might speak with a strong, non-native accent. The UK currently lies behind other EU nations in foreign language skills at school and in the workplace, therefore research into skill development has important educational and economic implications.

Previous research has used functional MRI to measure how the activity of functional systems in the brain changes as new speech sounds are learned. This work has described the integration of novel speech sounds into a talker's existing speech repertoire as it becomes more familiar. Within this, however, some talkers are more successful than others at attaining native-like pronunciation of new sounds, and this variability is correlated with the activation, size and structural composition of specific brain structures.

To date, the cognitive neuroscience of speech learning has assessed performance by measuring or judging the sounds of speech. However, there isn't a simple one-to-one relationship between how speech sounds in the air, and the underlying movements in the vocal tract. Therefore, an important missing piece of the puzzle is an understanding of how vocal articulations relate directly to brain activation during learning. Recent developments in MRI have shown that rapid 'real-time' anatomical scans can be used to create videos of the interior of the mouth and vocal tract, such that we can view how the lips, tongue and voice box are moved and configured to perform speech. We propose to combine real-time MRI with measures of brain structure and function to investigate the relationship between brain and behaviour during the learning of new speech sounds.

Our project will focus on short-term learning of novel and unfamiliar vocal sounds by native speakers of English, where the participants will aim to imitate the sounds accurately and with native-like pronunciation. In an MRI scanner, listeners will repeatedly produce these novel sounds, as well as native sounds of English, while scans of the brain will measure neural activity. Interleaved with these scans, we will collect real-time images of the vocal articulators during imitation. Acoustic recordings will be made using an in-scanner microphone, and we will additionally collect high-resolution images of brain structure from each participant. With these data, we will investigate vocal learning in terms of i) the functional brain systems supporting learning, ii) the acoustic accuracy of vocal output and iii) the accuracy of the movements generating the sounds, as well as the relationship between these elements. Further, we can explore how individuals differ in their performance of vocal learning in terms of meeting these acoustic and motor targets, and how this relates to their brain structure and function. Across a series of experiments, we will also investigate how novel sounds are sequenced into new words, and assess the effects of expertise on vocal learning by comparing English speakers with highly-proficient students of modern languages and professional beatboxers.

Our proposed approach is truly novel, with potential to make groundbreaking developments in the cognitive neuroscience of vocal communication. To deliver the project, we have assembled a uniquely qualified research team with shared and individual expertise in phonetics, cognitive neuroscience and MRI. The data will directly inform our understanding of language learning and accent acquisition. Further, our new methodology has potential future application to other questions, such as the assessment of brain and behaviour relationships in patients with speech impairments following brain injury.

The proposed research project bears direct relevance to language learning in adolescence and adulthood. Teenagers in the UK currently perform poorly in their use of foreign languages compared with students in the rest of Europe ("European Survey on Language Competences: Language Proficiency in England", National Foundation for Educational Research, 2013). Meanwhile, the demand for foreign language skills at all levels in the workforce is increasing, and the UK faces a growing deficit in the ability to supply adequately skilled individuals ("Languages: State of the Nation", British Academy, 2013). Thus, research on the mechanisms for developing new language skills speaks to issues concerning the educational and economic future of our country. More generally, research on the neural and behavioural correlates of vocal learning is of relevance to all users of spoken language, whether they are acquiring a language for the first time, working to improve a second language, or re-learning speech after a brain injury.

We have identified several potential beneficiaries of this research outside the academic community:

Students and teachers of modern languages: Interest in studying foreign languages has declined in the UK in recent years; moreover, there is an imbalance in uptake that favours students from higher socio-economic status backgrounds ("Languages: State of the Nation", British Academy, 2013). The proposed project will respond to these current issues. In planned impact activities in the short to medium term, we will engage primary and secondary school students' interest in language learning by illustrating the vocal articulatory system using the visually engaging medium of real-time MRI videos, and in entertaining contexts such as beatboxing performance. In the medium term, targeted articles for vocational publications will directly engage teachers with results of the project relevant to language education. Further, a planned database of real-time MRI videos of the vocal tract will be made available to language teachers in the medium to long term, to illustrate aspects of phonetics and the motoric correlates of speech in the classroom.

Education policy makers: In the medium term, the results of this project and the published materials will potentially be of interest to policy makers considering how to improve foreign language performance by UK students, for example by enhancing understanding of specific challenges in language acquisition such as individual differences in vocal learning.

NHS professionals: In the short to long term, speech and language therapists, neurologists, radiographers, radiologists and clinical scientists will be interested in the development of new methodologies to study vocal learning, for application in contexts such as recovery of speech after stroke.

Royal Holloway, University of London (RHUL) and Queen Mary, University of London (QMUL): The proposed work stands to enrich the cultural and educational experience of current and prospective students at RHUL and QMUL, by introducing them to the nature of research in a way that is academically accessible and visually engaging.

Journalists and media: In the short to medium term, the outputs of the proposed research will be communicated for publication in online, print and broadcast media. The use of real-time MRI in expert populations (e.g. beatboxers) will support communication of the findings in a way that is both intellectually accessible and culturally enriching.

General public: Vocal communication is central to everyday human experience, but many people have little insight into the exquisite complexity of the articulations underlying our speech. In the short to medium term, a range of planned public events will engage people of all ages and backgrounds with the method and results of the project, using a combination of live performance and scientific presentation to enhance scientific understanding of the brain and vocal behaviour.