Patient interface design for acoustic detection

A patient interface model for delivering a respiratory therapy to a patient via an air circuit from a respiratory therapy device, the patient interface model comprising:

• an inlet that is connectable with the air circuit;
• a plenum chamber integrated with the inlet and in fluid communication with the inlet, wherein the inlet and plenum chamber form a flow path for the respiratory therapy, wherein the plenum chamber is configured for coupling with a respiratory system of the patient for delivery of the respiratory therapy to the patient;
• and
• a positioning and stabilising structure configured to engage the plenum chamber with the patient,
• wherein the patient interface is adapted with one or more first model specific acoustical features in the flow path that are configured to produce an acoustic response to sound in the flow path that distinguishes the model of the patient interface from different patient interface models that have respectively different one or more model specific acoustical features.