Children born with a cleft lip and palate (CLP) are known to be at risk for speech-language disorders that impact academic and social emotional growth. Even at very young ages (<3 years), speech-language disorders are already observed. It is hypothesized that speech-language intervention delivered before the age of 3 years old could decrease the impact of CLP on speech-language development. This would result in a decreased need for speech-language therapy on the long-term and a reduced burden of care on children, families and health services. However, no evidence is yet available to support any specific model of early speech-language intervention in this population. Consequently, no standardized clinical practice guidelines are available yet. Symbolic gesture training in combination with verbal input expands the natural communication of young children including multimodal speech-language input (i.e., verbal and manual input) via caregivers who act as co-therapists. To contribute to the evidence-based practice in the field of cleft speech therapy, this research project aims to determine the effectiveness and feasibility of symbolic gesture training in one-year old children with CLP by comparing different intervention approaches based on perceptual, psychosocial and qualitative outcome measures.

Children with CP±L are known to be at risk for speech-language delays that impact educational and social-emotional growth. Early intervention in this population mostly focuses on improving verbal input via caregivers or professionals without including a multimodal language input. As stated above, no evidence is yet available for the effectiveness and feasibility of early intervention based on symbolic gesture training in combination with verbal input to improve speech-language skills in young children with CP±L. To contribute to the evidence-based practice in the field of early cleft palate speech intervention, this research project will focus on the effectiveness of symbolic gesture training in one-year old children with CP±L by comparing different intervention approaches based on quantitative and qualitative outcome measures. This project meets the need to evaluate the impact of early intervention on speech-language outcomes in children with CP±L as proposed by several researchers based on reviews regarding this topic.

The primary objective is to explore if children with CP±L who are enrolled in symbolic gesture training to support verbal in- and output at the age of 12 months have increased receptive and expressive language skills compared to children with CP±L who are enrolled in verbal training or not involved in any intervention at all.

The secondary objectives are:

2.1 To explore if children with CP±L who are enrolled in symbolic gesture training at the age of 12 months have improved speech skills, compared to children with CP±L who are enrolled in verbal training or not involved in any intervention at all; 2.2 To explore if children with CP±L who are enrolled in symbolic gesture training at the age of 12 months demonstrate more gesture use, compared to children with CP±L who are enrolled in verbal training or not involved in any intervention at all; 2.3 To explore if caregivers of children with CP±L who are enrolled in symbolic gesture training when their child is 12 months of age provide more frequent and more complex linguistic input to their child's utterances compared to caregivers of children with CP±L who are enrolled in verbal training or not involved in any intervention at all.

Inclusion Criteria:

• Born with cleft palate (with or without cleft lip)
• Having Dutch as mother tongue

Exclusion Criteria:

• syndromic cleft
• more than mild hearing loss (i.e. > 40dB hearing threshold bilaterally)
• neurosensory hearing loss
• cognitive delay
• motor delay

Data are stored in REDCap, an electronic data capture system (Harris et al., 2019). The research is carried out in accordance with the information security policy of Ghent University. Personal data are pseudo-anonymized at the level of data collection and anonymized at the level of data analysis. A separate file is created with the key to the code assigned to each participant. This file is stored separately from the other databases and is only accessible to the first and last authors or to the appointed replacement. Only anonymized data are used for analysis and in any type of documentation, reports or publications concerning this study.

All tests and recordings will be performed by two SLPs of the research group with experience in the diagnosis and treatment of speech and language disorders in children with CP±L. The annotation, analysis and scoring will be performed by the same SLPs. Both raters will analyze 100% of the video-recordings to calculate inter-rater reliability. To calculate intra-rater reliability, both raters will re-assess 20% of the recordings. The raters will not provide intervention to any of the included children and caregivers. They will be blinded for group allocation of the child and caregivers.