The goal of this clinical trial is to evaluate the efficacy of sibilant biofeedback treatment delivered via telepractice in six children ages 8:0-17;11 who present with distortions of /s/. The main questions it aims to answer are:

• Primary hypothesis: Biofeedback treatment for sibilants delivered via telepractice will produce positive gains compared to a no-treatment baseline phase.
• Secondary hypothesis: Participants will experience positive changes in social-emotional well-being after receiving biofeedback treatment for sibilants as reported by the participants and their guardians.

Following the initial evaluation, participants will be randomly assigned to transition from baseline to treatment at one of seven possible points, ranging from 4-10 baseline sessions in which /s/ production will be probed but not treated. All participants will then receive 20, 1-hour biofeedback treatment sessions over 10 weeks with a certified Speech-Language Pathologist via teletherapy, followed by three maintenance sessions.

Study 2 will evaluate children with residual speech sound disorder affecting /s/ (n = 6). Both male and female children will be recruited. Participants must be between 8;0 and 17;11 years of age at the time of enrollment.

Randomization. Following the initial evaluation to determine eligibility, participants will be randomly assigned to transition from the baseline to the treatment condition at one of 7 possible points, ranging from 4 to 10 baseline sessions in which /s/ production will be probed but not treated. All participants will then receive 20 sessions of /s/ production training over 10 weeks, followed by 3 maintenance sessions.

Intervention Delivery. All treatment will be provided on an individual basis by a certified speech-language pathologist. Treatment will be delivered over Zoom videoconference calls using a unique password-protected room for each participant. In the beginning of each session a standard probe eliciting /s/ in various contexts at the sentence, word and syllable levels will be elicited. Following the /s/ probes, the session will consist of relatively unstructured, highly interactive prepractice for 10 minutes, which is designed to provide instruction on the phonetic requirements for /s/ and shaping strategies to transform the child's current productions into accurate /s/. The remainder of the session will elicit up to 150 syllables/words or 40 minutes of practice, whichever occurs first. Practice will occur in blocks of 10 consecutive trials on the same item (e.g., 10 /sa/), after which a new item will be addressed (e.g., 10 /se/). Within each block, the clinician will provide qualitative (knowledge of performance) feedback as prompted by the research team's custom open-source software, Challenge Point Program (CPP). The CPP software prompts clinician actions such as delivery of knowledge of performance (KP) feedback, promoting increased fidelity in treatment implementation both within and across sites. It also enables systematic changes in practice difficulty based on participant performance, as follows: after the software presents a stimulus and the participant attempts to produce it, the clinician scores the response as 0 or 1 based on their clinical impression of an incorrect or correct production of /s/. Following each block of ten trials, the software automatically tallies the scores entered by the clinician and uses them to make adaptive changes in practice difficulty. When a participant demonstrates at least 80% cumulative accuracy at the session level, the participants will be advanced from syllable to word-level practice; if the cumulative session-level accuracy drops below 50%, the participants will be dropped back to the syllable level to decrease difficulty. In word-level practice, parameters are adjusted on a rotating basis so that as accuracy increases, either the frequency of feedback is reduced (80%-50%-20%-0%), clinician models are faded, or word shapes increase in complexity. Qualitative feedback (either biofeedback or verbal clinician feedback) will begin at 80% of trials and, contingent upon the participant's performance, will be systematically decreased to 0% .

Inclusion Criteria:

• Age between 8;0 and 17;11 years at the time of enrollment
• English as the dominant language (must have begun learning English by age 3, per parent report)
• Passes pure-tone hearing screening at 30 dB hearing level
• Passes brief examination of oral structure and function
• Less than 30% accuracy, based on consensus across 2 trained listeners, on a probe list eliciting fricative /s, z/ in various phonetic contexts at the word level
• No more than 3 sounds other than /s/ in error on the Goldman-Fristoe Test of Articulation-3 (GFTA-3)
• Diagnosis of ADHD, learning disability, dyslexia, or neurodiversity is admissible if participant meets cutoff scores on evaluation day 1
• History of CAS is admissible if participant meets cutoff scores on evaluation day 1
• Braces and removable retainers are admissible
• Access to a laptop or desktop computer and a quiet space for study sessions

Exclusion Criteria:

• Scaled score of 7 or higher on the Recalling Sentences and Formulated Sentences subtests of the Clinical Evaluation of Language Fundamentals-5 (CELF-5)
• History of permanent hearing loss (temporary hearing loss due to otitis media, including recurrent OM/tubes, is admissible)
• History of developmental disorder (e.g., Down syndrome, cerebral palsy)
• History of major brain injury, surgery, or stroke in the past year (mild concussion is admissible)
• Active diagnosis of epilepsy or other neurological disorder (permissible if well-controlled for at least 6 months)
• Current diagnosis of voice or fluency disorder
• Current presence of orthodontia that crosses the palate (braces and removable retainers are admissible)
• Lack of access to a laptop or desktop computer and a quiet space for study sessions