If a tree falls in the forest and there’s no one there to hear it, does it make a sound?
I have a feeling the Zen Monk who thought this was a mind bending cryptic puzzle was also a pot smoking fourteen year old who slept through Physics.
Those who answer ‘No’ invariably –an inaccurately– define sound as entirely a sensory response: the effect of electrical stimulus upon brain cognition by a vibrating eardrum. However, unless one is hallucinatory, human ability to sense sound is wholly dependent on an external source causing (air) molecules to vibrate. It is these vibrating particles that comprise sound, not one's ability to sense them.
To clarify, sound and the sense of hearing are two different things.
So, if a tree falls in the forest and there's no one there to hear it, yes, it still causes air molecules to vibrate and therefore makes a sound, independent of any individual capacity to sense those vibrations.
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Click on any link below to read all the articles in the three-part Spring/Summer 2003 AUDIO KOANS series exploring the relationship between zen wisdom and sound:
1. If a Tree Falls In The Forest...
2. Sound of One Hand Clapping?
3. Zhàozhōu's Dog