Question: how can we hear ?

Claire El Mouden answered on 19 Jun 2013:

We hear because sounds create pressure waves in the air that cause a thin membrane called our eardrum to vibrate. We have some tiny bones in the ear which then pick up these vibrations. These vibrations are then make a fluid in our ears move (in something called the cochlea) and then nerve cells detect this fluid movement and transmit a message to the brain. Our brain then decodes this information and make us understand it as sound!