A vent arrangement for a respiratory pressure therapy device may include one or a plurality of vents configured with a variable aperture for communicating a flow of breathable gas. The vent arrangement may be configured with a cross section profile exposed to the flow of breathable gas communicating through the vent that does not change as the aperture size changes. A vent arrangement may include a plurality of the vents and the aperture size of each vent may be controlled independently or together, and may be controlled according to one or more input signals from one or more sensors. Examples of suitable input signals include flow, pressure, noise, accelerometer outputs, orientation of a patient or presence of any obstructions. A patient interface or an air circuit may include the vent arrangement, or the vent arrangement may be configured to connect with a patient interface or an air circuit.