Figure 1

A photograph of the devices installed on the patient with a tracheostomy. A condenser microphone with a voice recorder and parts of a polysomnogram were set on the patient. A nasal prong connected with a polysomnogram was located at the entrance of the tracheostomy tube. A condenser microphone was located at a distance of 2–3 cm from the outer opening of the tracheostomy tube. Pulse oximetry, thoracic and abdominal bands were also set on the patient.