This project meets the need for evidence-based, cost-effective logopaedic practice in patients with an isolated cleft palate to eliminate passive speech disorders resulting from velopharyngeal insufficiency. The effectiveness of short-term intensive speech therapy programs using CPAP or SOVT exercises with a ventilation mask on velopharyngeal closure, speech intelligibility, hypernasality and HRQoL will be evaluated using a blocked-randomized sham-controlled trial.