Feasibility and Preliminary Effects of a Therapeutic Approach Using Ultrasound Visual Biofeedback in Children With AFI: a Pilot Randomized Clinical Trial.

Ultrasound Biofeedback Intervention (Experimental Group): The experimental intervention involves intensive speech therapy augmented with real-time ultrasound tongue imaging as visual feedback. A portable ultrasound system with a small microconvex transducer is used, positioned submentally (under the child's chin) to capture a midsagittal view of the tongue.

. The ultrasound transducer emits safe, high-frequency sound waves, and the reflected signals produce a dynamic image of the tongue's surface on a monitor. Specialized software (such as Articulate Assistant Advanced (AAA) by Articulate Instruments Ltd.) is utilized to display and synchronize the ultrasound images with speech output.

During therapy, the child can see a real-time outline of their tongue moving on the screen as they attempt target sounds. This visual biofeedback serves as knowledge of performance - it allows the child to compare their tongue shape and placement against the therapist's model or a predetermined target shape. For example, the clinician may instruct the child to "lift the back of your tongue" for a velar sound and the ultrasound image immediately shows whether the child's tongue dorsum is reaching the correct position. A custom head-stabilization apparatus is often used to keep the probe steady and ensure consistent imaging. Throughout the ultrasound-assisted practice, the therapist provides cues and coaching based on the visual information (e.g. telling the child to aim the tongue toward a certain position on the screen) in addition to the typical auditory and tactile cues.

Control Intervention:

Therapy Targets and Session Structure: Therapy targets are individualized for each child based on their speech error profile, focusing on phonemes and word shapes that are challenging due to CAS. Targets include specific phonemes (speech sounds) and various syllable structures (e.g., CV syllables, CVC words, consonant clusters, and multisyllabic words) that the child has difficulty producing. For instance, a child who cannot accurately produce lingual consonants might have targets like /s/, /ʃ/, or /k/ in simple syllables ("sa", "ka") and in words of increasing complexity ("sapato", "cavalo", etc.). Control Intervention (Waitlist): The control group will not receive the intervention during the study; they will only be monitored via assessments. This group will receive the intervention at the end of the study.

Therapeutic Objectives and Session Structure: Therapeutic objectives are individualized for each child based on their speech error profile, focusing on phonemes and word structures that pose challenges due to Childhood Apraxia of Speech (CAS). Objectives include specific phonemes (speech sounds) and various syllable structures (e.g., CV syllables, CVC words, consonant clusters, and multisyllabic words) that the child struggles to produce. For example, a child unable to accurately produce lingual consonants might target sounds such as /s/, /ʃ/, or /k/ in simple syllables ("sa," "ka") and in words of increasing complexity ("sapato," "cavalo," etc.). Each participant undergoes a series of therapy sessions throughout the intervention. Sessions are typically scheduled multiple times per week (e.g., two sessions weekly) over several weeks to accumulate a high volume of practice attempts. Each session lasts approximately 45 to 60 minutes, following the ULTRAX protocol.

Inclusion criteria

Clinical diagnosis of Childhood Apraxia of Speech (CAS) confirmed by assessment; Age between 5 and 16 years; Monolingual speakers of Brazilian Portuguese; Normal auditory, cognitive, and receptive language skills; Normal results on orofacial screenings.

Exclusion criteria

Hearing impairment or auditory processing disorders; Neurological, intellectual, or anatomical conditions affecting speech (e.g., cleft palate, cerebral palsy, dysarthria); Diagnosis of global motor development disorders; Bilingual speakers or individuals exposed to other languages at home.