Sample 5 - A tree falls in the forest and no one is around, does it make a sound?

Title: The Sound of Understanding

What you should know: The answer to the question, “If a tree falls in the forest and no one is around, does it make a sound?"

This is another example (see Chicken/Egg page X) where is it useful to specify what the question is asking and what the words in the question mean. To get to the answer, first we need to discuss how humans hear anything. It is important to realize that ‘hearing’ happens in the brain where neurons fire because they have received electrical signals from the ear.

Attempting to provide simplicity as well as greater detail, the process of hearing begins when vibrations of molecules in the air (i.e., sound waves) are captured by the outer ear and passed along to the ear drum, at which point the vibrations are transferred along delicate bones that vibrate appropriately to further send the information to the fluid-filled cochlea. The somewhat altered vibratory information is then sent to sensors in the organ of Corti where the mechanical wave information is converted into electric signals in neurons by little hair like cells. This ‘electrical sound information’ proceeds along a nerve, through the brainstem, the thalamus and eventually to the primary auditory cortex in the temporal lobe.

The key part of all that was the very beginning: “…vibrations of molecules in the air…” That, plus a brain, is what sound is! So, any occurrence that causes molecules in the air to move has the potential to be detected as a ‘sound.’ This potential is realized if there is a brain around to decode the vibrations into nerve signals into the sensation of sound. Therefore, the answer is that a tree causes molecules to vibrate, but if there are no brains around, the tree will not make a ‘sound.’

Why you should know it: It demonstrates that seemingly complicated (even purportedly unanswerable!) questions can be quite answered if investigated more thoroughly. Also, you can be that person at a party that actually has an answer to this question (and then have the experience of half the guests finding you interesting and the other half disliking your analytical nature.)

Further thoughts: More interestingly is the amusing topic of pondering how other organisms would experience ‘sound’ (i.e., what would their sound sound like?). Surely there are very few trees that do not have numerous organisms in its surrounding environment. Obviously there would be bacteria, and insects, but perhaps even small furry creatures or a bird or two. One could say there is a simple test to see if an organism can detect sound. In a forest or jungle, simulate the sounds of a tree breaking and beginning to fall, if the organism being tested doesn’t react, it probably doesn’t ‘hear’ much.

Additionally, if you are seeking an unanswerable question to clear your mind, like a Zen koan, it might be best to stick with the big, seeminly unanswerable question – where did the universe come from?

Finally, the description given above is sufficient for understanding how human process auditory information, but for those seeking to fully grasp the complexity of the situation, you could start by pondering what, if anything, is doing the ‘hearing’ (i.e., there are no little ears in the brain).