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The tree will make a sound, even if nobody heard it, simply because it could have been heard. The answer to this question depends on the definition of sound. We can define sound as our perception of air vibrations. Therefore, sound does not exist if we do not hear it. When a tree falls, the motion disturbs the air and sends off air waves.
Cold weather will cause some trees to shatter by freezing the sap, because it contains water, which expands as it freezes, creating a sound like a gunshot. [ 1 ] [ 2 ] The sound is produced as the tree bark splits, with the wood contracting as the sap expands.
Measured sound emissions by plants as well as differential germination rates, growth rates and behavioral modifications in response to sound are well documented. [1] Plants detect neighbors by means other than well-established communicative signals including volatile chemicals, light detection, direct contact and root signaling.
When a bolt strikes a tree it super-heats the sap throughout the tree and water in the sap turns to steam. "This happens in a split second," says Q13 FOX News Metoerologist M.J. McDermott.
Whether or not the falling tree makes a sound is irrelevant if no observer is present. An observer will be able to report any "tree-falling sounds" by detecting vibrations with equipment or his ears only if the observer is present at the time of the fall, (and as stated in the question, the observer exists but is not present).
Pitch is perceived as how "low" or "high" a sound is and represents the cyclic, repetitive nature of the vibrations that make up sound. For simple sounds, pitch relates to the frequency of the slowest vibration in the sound (called the fundamental harmonic). In the case of complex sounds, pitch perception can vary.
Now NASA is stepping in to provide some insight into what could actually be causing this scary pattern. NASA scientists believe the ominous noises could potentially be the "background noise" of ...
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