"If a tree falls in the forest with no one around does it make a sound?"
Seems the answer is no.

It creates a wave, but with no ear to receive it and no brain to interpret it, it can not be sound. It is a vibration, but the sound has to be heard to exist.

P.S, I got no help by Physics SE cause they said this question is off-topic and should part of philosophy.

  • 2
    Ok, if that's how you want to define "sound", but what is the point of a question if the answer is determined by one's verbal preferences? Your convention is not the standard one, by the way. According to Wikipedia, "sound is a vibration that propagates as a typically audible mechanical wave of pressure and displacement, through a transmission medium such as air or water", so it makes no difference if one hears sound or not.
    – Conifold
    May 10 '17 at 0:46
  • 2
    I'm voting to close this question because questions on the definitions or semantics of words or phrases are off-topic here as they are already well-answered elsewhere.
    – Conifold
    May 10 '17 at 2:35
  • There's no qualia en.wikipedia.org/wiki/Qualia of sound, if that's what you want to mean, but there's definitely physical sound, as already pointed out.
    – user19423
    May 10 '17 at 3:57
  • 1
    Being in a forest there may not be any human brain around but there are many other species with brains and auditory senses around. May 10 '17 at 5:16
  • The question is a philosophical question. How do we know whether a glass is fragile when it is surrounded by sponge? The glass will never break, but surely it can in the right circumstance. Carnap and some philosophers try to understand this question of disposition. May 10 '17 at 19:29

It depends on how you define sound and that is precisely the philosophical point. See the first dictionary entry here:

1 Vibrations that travel through the air or another medium and can be heard when they reach a person's ear or animal's ear.

As well as:

1.1 A thing that can be heard.

Both of these definitions say that a sound is a vibration that can be heard when they reach an ear. Does that mean that the vibration needs to reach an ear to fully be a sound? This dictionary seems to imply that is not the case, but it is not explicit.

In philosophy, one of the most important things you do is make a careful effort to fully explain the meaning of the terms you are using so as to clear up any ambiguities. There are arguments that the definition of "sound" is vague enough as to not require that the vibrations actually are heard by an ear, merely that they would be interpreted as a sound if they were. Of course there are also more strict definitions that require the vibrations to reach an ear for it to be a sound.

So the answer is: it depends on how you define sound. The philosophical aspect of this question isn't a metaphysical one about what trees or vibrations or anything else are like. It's an example of how philosophy requires you to use explicit definitions to clear up potential ambiguities. We know that if a tree falls it makes a vibration, we know that if that vibration hits an ear it will be heard as a sound, so is it a sound before that? That question is purely semantical and depends on the definition of "sound" whomever is asking is using.


The answer of course, depends greatly on definitions of "sound." Well, being a philosophy question it depends on a great many definitions, at the very least the definitions for "if," "a," "tree," "falls," "in," "the," "forest," "with," "no," "one," "around," "does," "it," "make," "a," and "sound." Absurdly pedantic? Terribly. But that's what happens when you try to play definition games in philosophy.

That all being said, the conclusion you arrived at actually is the exact same conclusion philosopher Alan Watts arrived at. This excerpt from one of his lectures bears a remarkable similarity to your argument:

If a tree falls in the forest and nobody is listening, does it make a noise? The answer in terms of modern science is perfectly clear, that the falling tree creates vibrations in the air and these become noise if and only if they relate to an eardrum and to an auditory nervous system. Sound is not something that exists in the external world, sound is a relationship between vibrating air and certain kinds of biological organisms. And therefore it is these organisms which confer what we call sound upon a vibration which in an earless world would make no noise.

  • there clearly is a difference bw a tree falling and snow falling in the forest, even if none hears. the tree has the disposition to make a sound when in contact with hard object violently, but not the snow. May 10 '17 at 19:48

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