If a tree falls in the forest and there is nobody there to hear it, does it make a sound? That’s not a trick question; the answer is no. “Sound” is a creation of the brain to represent a specific range of vibrations around 20 to 20,000 Hz. Vibrations in the air (as well as in liquids and solids) become sound when they are heard; until then they are just a small segment of the largely silent cacophony of vibrations in the air. What we hear is not the sound vibrating our eardrums, but what our brain thinks we should be hearing based on a large number of factors, our…