OBJECTIVE: Communication is a major issue for patients with tracheostomy who are supported by mechanical ventilation. The use of positive end-expiratory pressure (PEEP) may restore speech during expiration; however, the optimal PEEP level for speech may vary individually. We aimed to improve speech quality with an individually adjusted PEEP level delivered under the patient's control to ensure optimal respiratory comfort. METHODS: Optimal PEEP level (PEEPeff), defined as the PEEP level that allows complete expiration through the upper airways, was determined for 12 patients with neuromuscular disease who are supported by mechanical ventilation. Speech and respiratory parameters were studied without PEEP, with PEEPeff, and for an intermediate PEEP level. Flow and airway pressure were measured. Microphone speech recordings were subjected to both quantitative and qualitative assessments of speech, including an intelligibility score, a perceptual score, and an evaluation of prosody determined by two speech therapists blinded to PEEP condition. RESULTS: Text reading time, phonation flow, use of the respiratory cycle for phonation, and speech comfort significantly improved with increasing PEEP, whereas qualitative parameters remained unchanged. This resulted mostly from the increase of the expiratory volume through the upper airways available for speech for all patients combined, with a rise in respiratory rate for nine patients. Respiratory comfort remained stable despite high levels of PEEPeff (median, 10.0 cm H2O; interquartile range, 9.5-12.0 cm H2O). CONCLUSIONS: Patient-controlled PEEP allowed for the use of high levels of PEEP with good respiratory tolerance and significant improvement in speech (enabling phonation during the entire respiratory cycle in most patients). The device studied could be implemented in home ventilators to improve speech and, therefore, autonomy of patients with tracheostomy. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT01479959; URL: clinicaltrials.gov.