A measuring device for measuring in an ear canal includes a probe for insertion into an ear canal having an opening for letting air in to and out of the ear canal, and a pump for providing a pressure above a surrounding atmospheric pressure or below the surrounding atmospheric pressure, the pump including a housing with openings for inlet and/or outlet, where within the housing a piston element having piezo electric properties is disposed, one opening in the pump being operatively connected to the opening in the probe.