If a tree falls down in the forest and nobody hears it did it make a noise?

no it does not make a noise, a noise is an unwanted sound, if it can not be heard then it is not unwanted, however it does make a sound. sound is a form of energy thus hen the tree's gravitational potential energy it converted into kinetic energy during the falling motion, as it hits the ground its energy will be partially transferred into the earth and partially into the particles in the air thus creating sound waves