Articulation and representation of second language speech sounds

This award was provided as part of NSF's Social, Behavioral and Economic Sciences Postdoctoral Research Fellowships (SPRF) program. The goal of the SPRF program is to prepare promising, early career doctoral-level scientists for scientific careers in academia, industry or private sector, and government. SPRF awards involve two years of training under the sponsorship of established scientists and encourage Postdoctoral Fellows to perform independent research.

NSF seeks to promote the participation of scientists from all segments of the scientific community, including those from underrepresented groups, in its research programs and activities; the postdoctoral period is considered to be an important level of professional development in attaining this goal. Each Postdoctoral Fellow must address important scientific questions that advance their respective disciplinary fields.

Under the sponsorship of Dr. Jeff Mielke at North Carolina State University, this postdoctoral fellowship award supports an early career scientist examining how second language learners articulate second language speech sounds. Specifically, these studies examine whether speakers produce second language speech sounds the same as their first language speech sounds, and whether learners’ production strategies differ depending on the nature of the speech sounds.

As such, this research uses ultrasound, acoustic, and perception data of second language speech to look at the nature of category transfer of both consonants and vowels, in an effort to describe the acoustic and articulatory targets of speech sounds. More research about second language pronunciation is vital to improve pedagogical practices related to using technology in pronunciation instruction (specifically ultrasound and acoustic technologies), and this research provides information about acoustic, articulatory, and perceptual milestones for the acquisition of non-native sound contrasts.

A difficulty for defining the representation of speech sounds arises from the different phonetic nature of consonants and vowels. Consonants are definable by their constriction location and constriction degree, and thus gestural models are well-suited to explaining phonological processes involving consonants. Vowels, on the other hand, are produced with a relatively open vocal tract compared to consonants, and are therefore less easily definable by their articulatory targets.

The experiments included in this project compare hypotheses of gestural and acoustic models of L2 category formation. The first two experiments use acoustic, ultrasound, and perception data to examine how L1 English speakers produce and perceive L2 Mandarin fricatives and vowels compared to L1 fricatives and vowels. The second two experiments examine how L1 English speakers produce and perceive L2 Korean fricatives and vowels compared to L1 fricatives and vowels, again using acoustic, ultrasound, and perception data.

Learners in beginning, early-intermediate, and late-intermediate learning stages are recorded. These experiments contribute to theories of L2 category formation, which importantly have implications about the cognitive representation of consonants and vowels.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.