Abstract: A patient interface of a respiratory therapy system is provided, and includes a mask body; a mask seal secured to the mask body and configured to form a seal with the user's face, at least around the user's mouth; the mask body and mask seal being arranged to define an interior breathing chamber of the patient interface; and an inlet to the breathing chamber configured to receive a flow of breathable gases into the breathing chamber. To assist in allowing a user to speak clearly whilst wearing/using the patient interface, a user actuatable speech valve is provided on the patient interface and is operable to selectively occlude and open a speech flow path from the breathing chamber to atmosphere when the user wishes to speak.