Augmentative and Alternative Communication

The goal of this clinical trial is to learn if speech supplementation can improve speech intelligibility in children ages 7 to 17 years with cerebral palsy. The main questions it aims to answer are: * To what extent can speech supplementation improve intelligibility in children with CP compared with habitual speech produced without speech supplementation? * How much intelligibility change is necessary for meaningful improvement when children use speech supplementation strategies? Participants will: * complete speech and language assessments * complete a speech pre-test using habitual speech * learn a speech supplementation strategy with training from a speech-language pathologist * complete a speech post-test using the speech supplementation strategy * complete a speech repetition task where specific words are emphasized (emphatic stress) * use the previously learned speech supplementation strategy + emphasis on specific words while producing a set of sentences

Individuals with rare genetic conditions may experience a delay or loss of developmental skills. Many have limited verbal speech. The aim of this clinical trial is to examine how well a speech-generating device supports the communication skills of participants with a rare genetic condition. The speech-generating device is a communication program loaded onto an iPad. This is a crossover trial, meaning that each participant will receive both the treatment (device) and a control (usual care; no device) phase. The order in which each participant receives the device versus the usual care (no device) will depend on which group the participant is assigned to. The changes in communication in each phase will then be compared. During the trial, participants can expect to complete a series of assessments and attend a total of 2 x 1-hour therapy session per week for 6 weeks.