Current Projects

Mandarin-English Bilingual Speech Development

Bilingual children acquiring two languages may show different patterns of speech sound development compared to monolingual peers. Currently, many standardized speech assessments used in the field of speech-language pathology are designed for monolingual English speakers, making it difficult to evaluate bilingual children fairly. This project focuses on how shared and non-shared speech sounds between Mandarin and English contribute to children’s speech accuracy and development. By comparing children’s accuracy with sounds present in both languages versus those unique to one language, we hope to determine whether bilingual children demonstrate challenges that may be misinterpreted in clinical settings. The overall goal of the project is to provide clinicians with more accurate reference points and reduce the risk of over- or under-diagnosing speech sound disorders. This research contributes to more culturally and linguistically responsive assessment practices for bilingual children. 

Korean-English Bilingual Speech Development

Perception and production of speech sounds are tightly linked, and perception tends to precede production abilities in children and adults. This is especially relevant for second language learners. Learners who can perceptually differentiate two speech sounds (known as phonemes) in their second language, will also be better at producing the difference between the two phonemes. Bilinguals cannot simply ‘turn-off’ one of their languages. Therefore, speech perception in bilingual children must be approached with the idea that both languages will always affect perception.

Although it is known that during speech therapy, bilingual children’s productions of shared phonemes in English and Spanish tend to improve more quickly than phonemes unique to each language, it is not clear how generalizable this finding is to less related language pairs. It is likely that the ability to perceive acoustic differences between similar sounds across languages is related to more differentiation in production of the sounds across languages, but this must be tested. The goal of this study is to examine this cross-linguistic perception-production link with the guiding principle that perceptual tests could aid in determining which phonemes to target for speech treatment based on the individual knowledge of each bilingual child. The focus of the project is on children acquiring Korean and English, two languages less related than English and Spanish.

Learning sounds from native and non-native speech contexts

Understanding speech from an unknown speaker can be challenging at first, especially if the speaker has an unfamiliar accent. Research has shown that adults can rapidly adapt to unfamiliar speech including foreign accents and unfamiliar dialects, but children struggle more. Bilingual children are likely to come into contact with foreign-accented speech in their homes and communities, indicating a potentially more challenging language learning environment. Yet children in these communities do not tend to pick up foreign accents in their own speech. Additionally, challenging environments have been shown to lead to more robust learning, potentially leading to a more adaptive speech perception system.

Similar sounds can be difficult for second language learners to perceive. Have you ever heard someone say two words in a different language that you could not hear the difference between? For instance, in tonal languages such as Mandarin, a character could carry different meanings based on different tones used in various contexts, such as the character 好, which is pronounced as hǎo with a low-dipping tone, or hào with a falling tone. While listeners of Mandarin Chinese differentiate these two sounds aurally, they are also able to differentiate the meaning of it in utterances. The same thing happens for all language learners, especially in the early stages of learning a new language. Now imagine learning this from a non-native speaker who also struggles to produce the difference between these sounds. This is the challenging environment that bilingual children may face when learning sounds in a second language. This project aims to examine how children develop the ability to perceive new, difficult sounds produced by native and non-native speakers. It aims to examine both the benefits and challenges posed by such environments in the initial stages of learning.

Cross-linguistic influence of signed and spoken language

This project explores how hearing bimodal English–ASL bilinguals access their two languages during a verbal fluency task. Hearing bimodal bilinguals are people who are proficient in both a spoken language (e.g., English) and a signed language (e.g., American Sign Language-ASL). Many of these individuals later become educators or interpreters, which makes it important to understand how English and ASL may influence one another in real communication tasks. Verbal fluency tasks typically require participants to quickly produce as many words as possible in a given category or starting with a specific sound. In this study, “verbal” responses include both spoken English words and signed ASL responses. We are interested in how the activation of one language system might affect the other. For example, whether knowledge of English supports or interferes with producing signs in ASL, and vice versa. 

The main prediction is that activation of ASL will have very little effect on the number of correct responses produced in English. However, activation of English may have a greater impact on responses in ASL. In other words, English knowledge may serve as a resource for hearing bimodal bilinguals when accessing ASL vocabulary. The findings of this project will provide insight into the interaction between signed and spoken modalities and may guide teaching strategies to better support the growing community of hearing bimodal bilinguals working with the Deaf community.