Introduction: Cleft palate child are born with a naturally broken palate, and this anatomical structure has a significant effect on the development of speech and ability of expressive language. The velopharyngeal inadequacy (VPI) may still be in after the surgery, and therefore have speech characteristics such as hypernasality and compensatory articulation. Materials and Methods: In this study, subglottal pressure enhancement tools have been developed to encourage VPI child to improve speech production ability. Results: As a result of performing sub-glottal pressure improvement training on VPI child with this tool, the degree of nasalance and the articulation accuracy was improved. Conclusions: The tool improves the sub-glottal pressure and mouth cavity pressure in VPI child, effective for reducing hypernasality and articulation errors.