In reply to a post by pluralist:

"If a tree falls in a forest and no one is around to hear it, does it make a sound?"

Yes. You can check this with remote sensing.

It's not that simple.

A falling tree will definatley disturb air. Whether that can be classed as a sound is dependent on whether anything with working ears is in the vicinity. Its unlikely that in a forest there are no hearing animals in the required range, so I would argue yes it does.

In reply to a post by MattJessop:

A falling tree will definatley disturb air. Whether that can be classed as a sound is dependent on whether anything with working ears is in the vicinity. Its unlikely that in a forest there are no hearing animals in the required range, so I would argue yes it does.

I agree with your first sentence, but the word "sound" might be best used when considering only human perceptions in the context of this question.

In the absence of a human witness to the event then there would be no perception of sound and thus one can not with certainty and absolute confidence say that there was a sound.

So, if "sound" is only what humans can perceive then there is a very narrow frequency of sound waves that would be considered sound. If the sound is outside of human hearing range (eg ultrasound) does that mean it is not sound as humans cannot perceive it?

In reply to a post by ian72:

So, if "sound" is only what humans can perceive then there is a very narrow frequency of sound waves that would be considered sound. If the sound is outside of human hearing range (eg ultrasound) does that mean it is not sound as humans cannot perceive it?

Outside of the context of human hearing then for sure there are inaudible frequencies, e.g. dog whistles. However consider this further issue regarding the unobserved falling tree. Take this syllogism:

A tree falls in the forest
All trees in the forest make a sound when they fall
Therefore the tree made a sound when it fell.

Is it true to state that all trees in the forest make an audible sound to the human ear when they fall?

I've lost interest.

It is a philosophical and metaphysical debate about what "sound" is. I don't agree with the debate that sound only exists if a human being is there to hear it. I am more on the physics side - sound is made up of waves and the waves exist and impact on the environment whether or not something "hears" it. A philosophical debate for those that have the time to have it - but for me the sound waves exist and will affect the environment even if in a small manner and therefore the sound itself exists. I also am not convinced that any tree falling in the forest would be completely silent.

It is indeed a metaphysical question. Which is why it is still argued about by philosophers.

In terms of hearing, is tinnitus a sound?

In reply to a post by pluralist:

In terms of hearing, is tinnitus a sound?

It certainly is for me