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Long, H. L., Christensen, L., & Hustad, K. C. (in preparation). Prelinguistic development and motor speech disorders: A scoping review.

Prelinguistic development and motor speech disorders: A scoping review

The goal of the present scoping review is to support the early identification of motor speech disorders through the study of prelinguistic vocal and communicative behaviors in infancy. This will be achieved by comprehensively reviewing manuscripts evaluating prelinguistic vocal development in infants retrospectively or prospectively identified as being diagnosed with (or at risk for) a MSD, specifically, dysarthria or CAS. The proposed research will support this goal by reviewing commonly observed populations at risk, prelinguistic variables, and prelinguistic measures used across studies to date. The purpose is to identify gaps in the current literature base to support future research in this area.

Long, H. L., Eichorn, N., & Oller, D. K. (under review). A probe study on vocal development in two infants at risk for cerebral palsy.

A probe study on vocal development in two infants at risk for cerebral palsy.

The present work examined the utility of tracking canonical babbling ratios longitudinally as a measure of onset and consolidation of canonical babbling in two infants at risk for cerebral palsy. We collected all-day home audio recordings from both infants between 5-16 months of age. Canonical babbling ratios were calculated from five-minute segments and follow-up diagnostic data were collected around 24 months. Ten typically developing infants were included for comparison at four age points. Both the at-risk infants and the typically developing infants demonstrated greater variability than expected in their canonical babbling ratios over time. The infants at risk demonstrated somewhat delayed trajectories of CBRs compared to the TD infants. The two were later diagnosed with different levels of cerebral palsy and speech impairment severity. Studying canonical babbling and other prelinguistic milestones in this population may inform our perspective of the involvement of the motor system in the vocal domain.

El Amin, M., Borders, J. C., Long, H. L., Keller, M. A., & Kearney, E. (under review). Open science practices in communication sciences and disorders: A survey.

Open science practices in communication sciences and disorders: A survey

Purpose: Open science is a collection of practices that seek to improve the accessibility, transparency, and replicability of science. Though these practices have garnered interest in related fields, it remains unclear whether open science practices have been adopted in the field of communication sciences and disorders (CSD). This study aimed to survey the knowledge, implementation, and perceived benefits and barriers of open science practices in CSD.

Method: An online survey was disseminated to researchers in the United States actively engaged in CSD research. Four core open science practices were examined: Pre-Registration, Self-Archiving, Gold Open Access, and Open Data. Data were analyzed using descriptive statistics and regression models.

Results: Two-hundred and twenty-two participants met inclusion criteria. Most participants were doctoral students (38%) or assistant professors (24%) at R1 institutions (58%). Participants reported low knowledge of pre-registration and gold open access. There was, however, a high level of desire to learn more for all practices. Implementation of open science practices was also low, most notably for pre-registration, gold open access, and open data (<25%). Predictors of knowledge and participation, as well as perceived barriers to implementation are discussed.

Conclusion: Though participation in open science appears low in the field of CSD, participants expressed a strong desire to learn more in order to engage in these practices in the future.

Long, H. L., Ramsay, G., Bowman, D. D., Burkhardt-Reed, M. M., & Oller, D. K. (under review). Canonical babbling in vocal turn taking and independent vocal play.

Canonical babbling in vocal turn taking and independent vocal play

There is a growing body of research emphasizing the role of social and endogenous motivations in human development. The present study evaluated canonical babbling across the second-half year of life using all-day recordings of 98 infants participating in a longitudinal study. Canonical babbling ratios were calculated from human coding along with Likert-scale ratings on vocal turn taking and vocal play in each segment. Ratios across all infants were significantly elevated during high turn taking and also during high vocal play. We conclude that both social and endogenous motivations may drive infants’ tendencies to produce their most advanced vocal forms.

Long, H. L., Mahr, T. J., Natzke, P., Rathouz, P. J., & Hustad, K. C. (2022). Longitudinal change in speech classification between 4 and 10 years in children with cerebral palsy, 00, 1-10.

Longitudinal change in speech classification between 4 and 10 years in children with cerebral palsy

Aim: To examine speech impairment severity classification over time in a longitudinal cohort of children with cerebral palsy (CP).

Method: A total of 101 children (58 males, 43 females) between the ages of 4 and 10 years with CP participated in this longitudinal study. Speech severity was rated using the Viking Speech Scale (VSS), a four-level classification rating scale, at 4, 6, 8, and 10 years (age 4 years: mean = 52 months [3 SD]; age 6 years: mean = 75 months [2 SD]; age 8 years: mean = 100 months [4 SD]; age 10 years: mean = 125 months [5 SD]). We used Bayesian mixed-effects ordinal logistic regression to model (1) the extent to which speech severity changed over time and (2) patterns of change across age groups and classification rating group levels.

Results: VSS ratings decreased (speech severity became less severe) between 4 and 10 years of age. Children who were first classified in VSS levels I, II, or III at age 4 years had a high probability of staying at, or improving to, VSS level I by 10 years. Children who were first classified in VSS level IV at 4 years had a high probability of remaining in VSS level IV at 10 years.

Interpretation: Early speech performance is highly predictive of later childhood speech abilities. Children with any level of speech impairment at age 4 years should be receiving speech therapy. Those with more severe speech impairments should be introduced to augmentative and alternative communication as soon as possible.

Koopmans, C., Sakash, A., Soriano, J., Long, H. L., & Hustad, K. C. (2021). Functional communication abilities in youth with cerebral palsy: Association with impairment profiles and school-based therapy goals. Language, Speech, and Hearing Services in Schools, 1–16.

Functional communication abilities in students with cerebral palsy: Association with impairment profiles and school-based therapy goals

Aim. The aim of this study was to examine the relationship between functional communication skills, underlying speech, language, and cognitive impairments, and school-based speech pathology services in students with cerebral palsy (CP).

Method. Thirty-five participants with CP who had active Individualized Education Programs (IEPs) were classified according to the Communication Function Classification System (CFCS). Participants completed laboratory assessments of speech, receptive language, executive functioning, and non-verbal cognition. Each participant’s speech and language IEP goals were coded into treatment units, then categorized into seven, mutually exclusive target goal areas. Non-parametric analyses were employed to examine differences among CFCS groups in the number of deficit areas and the number of goal areas from the IEP. Descriptive analyses were used to evaluate the extent to which deficit areas and goal areas in the IEP co-occurred by CFCS level.

Results. Those in more involved CFCS levels demonstrated more severe speech, receptive language, and cognitive impairments. However, there were no significant differences in the number of deficit areas across CFCS group. Regardless of CFCS level, there were no differences in the number of treatment goals specified in the IEP. Literacy was the only goal area addressed across all CFCS levels. Those in the most involved CFCS levels had AAC goals, but those with more moderate restrictions on functional communication who also had markedly reduced speech intelligibility did not typically have speech or AAC goals.

Interpretation. Individuals with CP across CFCS levels demonstrate variability in their underlying deficit profiles, suggesting that measures of both functional communication and of underlying deficits are necessary to provide a complete picture of communication needs. Literacy goals were common across all CFCS levels, but AAC goals were limited to the most severely involved individuals, suggesting that continuing education may be necessary to support SLPs in developing treatments involving the integration of AAC and speech to foster functional communication at school.

Gipson, T. T., Ramsay, G., Ellison, E. E., Bene, E. R., Long, H. L., & Oller, D. K. (2021). Early vocal development in tuberous sclerosis complex. Pediatric Neurology, 125, 48-52.

Early vocal development in tuberous sclerosis complex

Objective: Our goal was to assess for the first time early vocalizations as precursors to speech in audio-video recordings of infants with tuberous sclerosis complex (TSC).

Methods: We randomly selected 40 infants with TSC from the TSC Autism Center of Excellence Research Network data set. Using human observers, we analyzed 74 audio-video recordings within a flexible software-based coding environment. During the recordings, infants were engaged in developmental testing. We determined syllables per minute (volubility), the number of consonant-vowel combinations, such as ‘ba’ (canonical babbling), and the canonical babbling ratio (canonical syllables/total syllables) and compared the data with 2 groups of typically developing (TD) infants. One comparison group's data had come from a laboratory setting, while the other's had come from all-day Language Environment Analysis recordings at home.

Results: Compared with TD infants in laboratory and all-day Language Environment Analysis recordings, entry into the canonical babbling stage was delayed in the majority of infants with TSC, and the canonical babbling ratio was low (TD mean - 0.346, SE - 0.19; TSC mean - 0.117, SE - 0.023)). Volubility level in infants with TSC was less than half that of TD infants (TD mean - 9.82, SE - 5.78; TSC mean - 3.99, SE - 2.16).

Conclusions: Entry into the canonical stage and other precursors of speech development were delayed in infants with TSC and may signal poor language and developmental outcomes. Future studies are planned to assess prediction of language and developmental outcomes using these measures in a larger sample and in more precisely comparable recording circumstances.

Burkhardt-Reed, M. M., Long, H. L., Bowman, D. D., Bene, E. R., & Oller, D. K. (2021). The origin of language and relative roles of voice and gesture in early communication development. Infant Behavior and Development, 65, 101648.

The origin of language and the relative roles of voice and gesture in early communication development

Both vocalization and gesture are universal modes of communication and fundamental features of language development. The gestural origins theory proposes that language evolved out of early gestural use. However, evidence reported here suggests vocalization is much more prominent in early human communication than gesture is. To our knowledge no prior research has investigated the rates of emergence of both gesture and vocalization across the first year in human infants. We evaluated the rates of gestures and speech-like vocalizations (protophones) in 10 infants at 4, 7, and 11 months of age using parent-infant laboratory recordings. We found that infant protophones outnumbered gestures substantially at all three ages, ranging from >35 times more protophones than gestures at 3 months, to >2.5 times more protophones than gestures at 11 months. The results suggest vocalization, not gesture, is the predominant mode of communication in human infants in the first year.

Oller, D. K., Ramsay, G., Bene, E., Long, H. L., & Griebel, U. (2021). Protophones, the precursors to speech, dominate the human infant vocal landscape. Philosophical Transactions of the Royal Society B: Biological Sciences, 376(1836), 20200255.

Protophones, the precursors to speech, dominate the human infant vocal landscape

Human infant vocalization is viewed as a critical foundation for vocal learning and language. All apes share distress sounds (shrieks and cries) and laughter. Another vocal type, speech-like sounds, common in human infants, is rare but not absent in other apes. These three vocal types form a basis for especially informative cross-species comparisons. To make such comparisons possible we need empirical research documenting frequency of occurrence of all three.

The present work provides a comprehensive portrayal of these three vocal types in the human infant from longitudinal research in various circumstances of recording. Recently the predominant vocalizations of the human infant have been shown to be speech-like sounds, or “protophones”, including both canonical and non-canonical babbling. The research shows that protophones outnumber cries by a factor of at least five based on data from random-sampling of all-day recordings across the first year. The present work expands on the prior reports, showing the protophones vastly outnumber both cry and laughter in both all-day and laboratory recordings in various circumstances. The data provide new evidence of the predominance of protophones in the infant vocal landscape and illuminate their role in human vocal learning and the origin of language.

Long, H. L., Bowman, D. D., Yoo, H., Burkhardt-Reed, M. M., Bene, E. R., & Oller, D. K. (2020). Social and endogenous infant vocalizations. PLoS ONE, 15(8), e0224956.

Social and endogenous infant vocalizations

Research on infant vocal development has provided notable insights into vocal interaction with caregivers, elucidating growth in foundations for language through parental elicitation and reaction to vocalizations. A role for infant vocalizations produced endogenously, potentially providing raw material for interaction and a basis for growth in the vocal capacity itself, has received less attention. We report that in laboratory recordings of infants and their parents, the bulk of infant speech-like vocalizations, or “protophones”, were directed toward no one and instead appeared to be generated endogenously, mostly in exploration of vocal abilities. The tendency to predominantly produce protophones without directing them to others occurred both during periods when parents were instructed to interact with their infants and during periods when parents were occupied with an interviewer, with the infants in the room. The results emphasize the infant as an agent in vocal learning, even when not interacting socially and suggest an enhanced perspective on foundations for vocal language.

Oller, D. K., Griebel, U., Bowman, D. D., Bene, E. R., Long, H. L., Yoo, H., & Ramsay, G. (2020). Infant boys are more vocal than infant girls. Current Biology, 30, R417-429.

Infant boys are more vocal than infant girls

Although it is generally assumed females have a language advantage over males, Oller et al., studying all-day recordings of 100 infants, found that boys in the first year of life produced more speech-like vocalizations than girls and that the effect size was more than four times larger than the commonly reported female language advantage.

Oller, D. K., Caskey, M., Yoo, H., Bene, E. R., Jhang, Y., Lee, C.-C., Bowman, D. D., Long, H. L., Buder, E. H., & Vohr, B. (2019). Preterm and full term infant vocalization and the origin of language. Scientific Reports, 9, 14734.

Preterm and full term infant vocalization and the origin of language

How did vocal language originate? Before trying to determine how referential vocabulary or syntax may have arisen, it is critical to explain how ancient hominins began to produce vocalization flexibly, without binding to emotions or functions. A crucial factor in the vocal communicative split of hominins from the ape background may thus have been copious, functionally flexible vocalization, starting in infancy and continuing throughout life, long before there were more advanced linguistic features such as referential vocabulary. 2-3 month-old modern human infants produce "protophones", including at least three types of functionally flexible non-cry precursors to speech rarely reported in other ape infants. But how early in life do protophones actually appear? We report that the most common protophone types emerge abundantly as early as vocalization can be observed in infancy, in preterm infants still in neonatal intensive care. Contrary to the expectation that cries are the predominant vocalizations of infancy, our all-day recordings showed that protophones occurred far more frequently than cries in both preterm and full-term infants. Protophones were not limited to interactive circumstances, but also occurred at high rates when infants were alone, indicating an endogenous inclination to vocalize exploratorily, perhaps the most fundamental capacity underlying vocal language.

Long, H. L., Oller, D. K., & Bowman, D. D. (2019). Reliability of listener judgments of infant vocal imitation. Frontiers in Psychology, 10, 1340.

Reliability of listener judgments of infant vocal imitation

There are many theories surrounding infant imitation; however, there is no research to our knowledge evaluating the reliability of listener perception of vocal imitation in prelinguistic infants. This paper evaluates intra- and inter-rater judgments on the degree of "imitativeness" in utterances of infants below 12 months of age. 18 listeners were presented audio segments selected from naturalistic recordings to represent in each case a parent vocal model followed by an infant utterance ranging from low to high degrees of imitativeness. The naturalistic data suggested vocal imitation occurred rarely across the first year, but strong intra- and inter-rater correlations were found for judgments of imitativeness. Our results suggest salience of the infant's vocal imitation despite its rare occurrence as well as active perception by listeners of the imitative signal. We discuss infant vocal imitation as a potential signal of well-being as perceived by caregivers.