Most of us take sound for granted as well as were just brought up with knowing exactly what it is. We never needed a definition for it. I found Chapter 11 to be interesting especially when discussing the 2 different definitions of sound, the physical and perceptional. The physical definition is pressure changes in the air or other medium. Whereas the perceptional definition is the experiences we have when we hear something. Both concepts make sense and are very interesting and eye opening to how we hear sounds. I loved how they used the question I think is safe to say we’ve all have heard before, “if a tree falls in the forest and no one is there to hear it, does it make a sound?” as a example to describe the 2 definitions. Of course the answer is yes to one of the definitions and no to the other. The answer is yes according to the physical explanation because of when the tree falls it causes pressure changes whereas the answer to the perceptional explanation is no because we did not experience the sound.