Exploratory Trial of the "HiDongDong" Language Rehabilitation App for Articulation Delay.

Inclusion Criteria: 1. Children aged 2 years to under 14 years 2. Persistent difficulties in speech sound production, or reduced speech intelligibility that interferes with communicative participation, resulting in limitations in social participation, academic performance, or daily activities 3. Articulation developmental delay suspected based on U-TAP results, with articulation performance more than 1 standard deviation below the mean for the same age group (-1SD) 4. Sufficient cognitive ability to follow simple instructions via a mobile device (tablet) 5. For children under 7 years of age: a caregiver who has received sufficient explanation of the study purpose and procedures and has voluntarily provided written informed consent 6. For children aged 7 years or older: voluntary assent from the child after sufficient explanation of the study purpose and procedures by the investigator, in addition to written informed consent from the caregiver Exclusion Criteria: 1. Caregiver or child does not consent to study participation, or withdraws consent during the study 2. U-TAP results indicate articulation development within the normal range, with no suspicion of articulation developmental delay 3. Difficulty understanding simple instructions or participating in assessments and training due to moderate or severe cognitive impairment, attention deficit, autism spectrum disorder, or similar conditions 4. Significantly limited speech production due to neuromuscular or anatomical causes, including severe visual impairment or visual field deficits, hearing impairment, cleft palate structural abnormalities, or severe oral/facial muscle dysfunction, resulting in difficulty with articulation 5. Inability to continue study participation due to acute illness or other conditions that may affect assessment or training during the study period, or unwillingness of the caregiver or child to continue participation 6. Determination by the principal investigator that study participation may pose a risk to the safety or well-being of the child Any one of the above exclusion criteria is sufficient for exclusion.