Acoustic characterisation of a CPAP device for the treatment of sleep apnoea

Sleep apnoea is a disorder in which a person has irregular, paused breathing during night sleep. Currently, the most used therapy consists in the application of a continuous positive airway pressure (CPAP) to the respiratory tract by a special machine, which serves as an air pump, controlled through a mask that covers the patient's nose and/or mouth. The scope of the present study is to probe a commercial CPAP machine from an acoustic viewpoint. The sound power emitted by the machine has been measured through acoustic intensity and acoustic pressure methods. Different types of masks have been compared by detecting the associated noise via pressure method. The issue of acoustic drainage aimed at reducing the overall emitted noise has also been considered: to this purpose, a fluid dynamic FVM analysis has been carried out on a 3D model representing the mask hose and the CO2 discharge system.