Well at the root of this question is what is classified as "sound" if it is what is received when the frequency hits the ear drums and vibrates then no it can't until there is something to hear it be it human or animal. Until there is a receptor to pick up or tune in there is no "sound" like a dog whistle to humans it makes no sound but to dogs it certainly does make a sound a very high pitched sound!

Another example is radio waves we can not hear them at all but they are all around us even right now there are bands playing music and people talking about the news and police officers saying "I'm there now, lets get him" fire men and ambulance drivers, CB people and so much much more all right now all around you and you hear nothing until you have the proper equipment to receive and amplify these signals to an audible level.

All of that is not classified as "sound" until we actually hear it but it is there always all around us, including thought and I don't doubt it someday we'll have a radio that can tune into that frequency too.

This leads me into a very very interesting lesson from The Secret Teachings of The Rosicrucians by Magnus Incognitus

This will blow your mind!!!!

Take a top and start it spinning you have movement and lets say this top instead of slowing down increases speed indefinitely. This first increase is a low hum Next a medium hum as this goes faster and faster this hum increases higher and higher pitch as well louder and louder. From this very high pitched hum next it goes beyond the human capacity of hearing, it sounds like it goes silent but as I said before a dog would hear it. This goes higher still and now it is starting to get hot, it feels a little warm but as it keeps spinning it heats up more and more hotter and hotter until it feels near burning hot! Now it starts glowing a dull dim red but as it keeps increasing in speed this glows brighter and brighter changing from red to orange then yellow, green, blue, indigo and violet then bright white and gets very bright white and next it seems to go out of the visible spectrum into infra red through to ultra violet. Next it climbs in the lower radio waves spectrum (yes the same radio spectrum that you listen to music on) it keeps spinning faster faster this goes higher through the radio spectrum into Gama waves and Micro waves and Ex-ray waves but it keeps spinning until it has gone through all waves and all spectrums and is so fast now it has finely hit Thought waves, the speed of thought it self it is now a thought!

Think of your Bible and the word and all was made from the word, to make that top would be everything I just wrote in reverse.

Yes, it makes an sound because it is an physical tree living in an physical world and when it falls down from rotting or being cut it makes an sound and we may not hear it because we are not there but the animals and insects will.

If you stop and tune your self into the world of the animals and insects. You will be surprise what you will hear. The sounds of nature or quite remarkable. Also if you listen to nature and pay attention to nature you will learn a lot.

You can literally feel danger in the air as it vibrates danger and your body will pick it up through the waves of energy passing through the air.

Now there are many sounds we do not pick up with our ears even when we are there simply because we have maybe unconsciously decided to tune that particular sound out of our conscious hearing now the subscious maybe set at recording but the conscious does not hear it at all for it has completely tune it out. I know for I have done this unintensionally for I had gotten so engrossed in reading an book or doing something that I did not hear something or someone at first until something brings my attention back to it than I hear it. Does that means it not not make an sound NO it means it made an sound but I was not paying any attention to it.

Now there are things if you you give it your attention than you give it power over you and it becomes bigger an stonger but as you take your attention away from it it dwindles down to nothingness now that is an different story. Example would be fear of something if you give it your full attention than you will become even more afraid and it will have more power over you. But this is the begining of another question or story.

The animals and insects communicate all the time. Everything is real and not imaginary once you bring it out of the imagination and creates it than it becomes solidfied in the real world than it is real.

The physical world was create before us humans were created but it was created for us because God knew he was going to create physical human being in his own image. God placed us here in this physical world so we could survive, live and enjoy life as an physical human being.

I have not swam in the oceans, the seas, or touch the waters of them but they are real. So, I don't have to see them in order for them to be real.

Sounds can be made if there is no one there to hear it. Germs are there when we can see them. Light rays are there that we can't see. The falling tree produces vibrations. These vibrations are sensed differently by different organs and different organisms. The vibrations would be felt and heard by a person, and felt by a deaf person but not heard. The vibrations might be felt by other trees causing a visible vibration that the people can see. A deaf person could still hear and see the vibration.

I love this quintessential query into the metaphysical world; as a teacher of philosophy allow me to answer this question using the 4 main philosophies.

Of course it makes a sound; the Father knows when a sparrow falls (Idealist).

Falling objects result in a sound, whether or not it is audible and distinguishable to the human ear is unknown (Realist).

No one is there to see the tree fall, to hear it fall, so it is of little concern to me (Pragmatist).

Define "tree." (Existentialist)

No doubt by now many of you are getting down right sick and tired of me--but life, philosophy, whatever, is like physics: redundant and omnipotent. As humans our culture (experiences) and reinforces (family, friends, community) and language determine our reality.

Great question!

while we're on sences, explain colours. lets say your eyes see my green as red lets say. then if i try to explain my red i can only use examples that would and could not it truer or less true what colour you see. the possibilities, there could be someone out there that lives in a real physedelic world but i guess ill never be certain.