The Perception

If a tree exists outside of perception then there is no way for us to know that the tree exists. So then, what do we

mean by existence', what is the difference between perception and reality? Also, people may also say, if the tree exists outside of perception as common sense would dictate, then it will produce sound waves. However, these sound waves will not

actually sound like anything. Sound as it is mechanically understood will occur, but sound as it is

understood by sensation will not occur. So then, how is it known that 'sound as it is

mechanically understood' will occur if that sound is not perceived?