So, recall from physics, whenever a mechanical wave is propagating through air and then it hits some type of liquid boundary, there is a good amount of resistance that exists at that boundary. And to actually transmit our mechanical wave from air into liquid, we have to amplify our force. So basically, inside the inner portion of the ear, we no longer have air. We have a fluid type, a liquid of a type known as the periomph. And as this air fluid boundary, we have a considerable amount of resistance to the mechanical waves. And to overcome this resistance, we have to amplify our force.