Social Influences on Sensorimotor Integration of Speech Production and Perception During Early Vocal Learning

Study Overview
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Brief Summary
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The goal of this study is to investigate the role of social factors on speech learning, including production and perception, in infants ranging in age from  7-18 months. Infants have either typical hearing or sensorineural hearing loss. The main prediction of the study is that social reinforcement will engender improvements in vocal learning above and beyond gains in hearing in infants with hearing loss. As part of this study: The parent and infant engage in a free play session in the playroom while the investigator cues the parent to say simple nonsense words; Infants hear playback of the same words during a second phase.

Detailed Description
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Infant vocal learning and development is embedded in a social feedback loop. Babbling vocalizations catalyze consistent responding by caregivers, and these predictable social reactions provide opportunities for infant learning. Naturalistic data and experimental manipulations have verified both the potency of babbling for eliciting social-vocal responses from caregivers, and the efficacy of social feedback for rapid advances in infant vocal learning. The impact of infant hearing loss, however, has never been studied with regard to the social feedback loop. Infants born with significant sensorineural hearing loss may be deprived not only of early auditory experience but of social experience as well. The reduction or elimination of social feedback to immature vocalizations, either by reduced or unpredictable parental responses or by infants' lessened ability to perceive those responses, is likely to have strong effects on learning and development of speech. Restoring hearing via cochlear implants improves auditory perception but does not remediate lost social learning opportunities or provide knowledge of how to learn from social partners. The goal of this project is to investigate how social interactions mediate the ability to incorporate phonological patterns of the language environment into vocal repertoires in infants with typical hearing versus infants with hearing loss (who either continue with hearing aids or experience gains in hearing via receipt of a cochlear implant). The investigators' method is to remotely observe naturally-occurring interactions between infants and a parent while recording their vocalizations; the investigators instruct the parent via headphones to provide vocal-social reinforcement to the infants when they produce a babbling utterance. Infant-parent dyads in a yoked control condition receive the same schedule of social reinforcement cues as a matched pair, which is random with respect to actual infant utterances in the control condition.

Official Title
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Social Influences on Sensorimotor Integration of Speech Production and Perception During Early Vocal Learning

Conditions
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Speech, Sensorineural Hearing Loss

Intervention / Treatment
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* Behavioral: vocal-social reinforcement


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: infants ca. 7-16 months of age at study onset Infants less than 24 months of age (for follow-up visits only) At least one English-speaking or Spanish-speaking parent in the home who can participate in the study Subjects will include infants with typical hearing, hearing loss, or hearing loss remediated by a hearing aid or cochlear implant. Exclusion Criteria: infants who are not exposed to English or Spanish in the home infants who do not have a parent who can participate in the study will be excluded (Caregivers who are not parents will not be eligible to participate in the study)

Ages Eligible for Study
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Minimum Age: 7 Months
Maximum Age: 24 Months

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: We have a parallel design in which parent-infant dyads are assigned to either the intervention or to a random control group.
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Experimental<br>Parents are instructed to say nonsense words in response to infant babbles with a conserved phonological form as infant plays. | Behavioral: vocal-social reinforcement<br>* experimental manipulation of social reinforcement in response to vocalizations<br>|
| No Intervention: Control<br>Parents are instructed to say nonsense words at random times with a conserved phonological form as infant plays. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Vocal Codes During Study Visit | Infant vocalizations are assigned to categories of speech maturity, and frequency of each category will be assessed before, during, and after the cued responses from parents. | Measured over the course of 30 minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Vocal Codes Between Visits | The same categories of speech maturity will be used at each study visit, allowing comparison of speech composition over time. | Measured at initial visit and up to three additional times between 30-180 days following the initial visit | 
| Perception | Infants will hear a recording of the same nonsense words spoken by their parent, and investigators will measure how long the infant looks in the direction of the word (how long the infant pays attention to each word). | Measured at initial visit and up to three additional times between 30-180 days following the initial visit | 
| MacArthur Communicative Development Inventory | This vocabulary inventory form will measure the breadth of the infant's known words and early sentence use. | assessed at 16 months and/or 6 months after initial visit |