Jesus H. Christ! Ok, I'll revise my answer to any sound any living thing can hear.

Also, think about deaf people. Do you ask them if they hear the sound? They feel vibrations, yes, but they do not hear sound without the ear. The inclusion of the functional ear is crucial for there to be sound.

"Sound is a function of the ears though"

Wrong. Sound is a wave that is caused by the back and forth movements of the medium it is traveling in. The waves of sound signify changes in air pressure; the presence of sensory organs has NOTHING to do with the existence of sound. The human ear just responds to a spectrum of frequencies it can detect, much like our eyes are tuned to register a small portion of the electromagnetic spectrum. Do you content that infrared waves don't exist because they can't be detected by our eyes? No, unless you modify the definition of "light" to "radiation that is only perceptible to human eyes". Same deal with sound. And even if you were to make a modification to the question and have it say, "does it make an AUDIBLE sound," you still wouldn't have a case because the frequency range would still be within that 20Hz - 20kHz range detectable by the human ear. Subjective perception or the lack thereof does not affect the answer one way or another. It's almost as absurd as saying if a nuclear bomb were to be detonated on Venus and we didn't see it, it technically (by your logic) would not have emitted any light.

"to the human, without hearing the tree fall, it does not make a sound, even though it does push energy out in the form of vibrations and pressure changes."

You're assuming ears or sensory equipment are necessary for sound to technically exist, which is wholly inaccurate. Scientifically, sound is an instantaneous change in air pressure caused by vibrating particles, whether or not something is present to sense it or not. If you want to argue philosophy, this is not a discussion to argue it in, because science refutes your argument from the get go.

http://www.glenbrook.k12.il.us/GBSSCI/PHYS/Class/sound/u11l1c.html

That depends on whether you find your flatulence to be of pleasing aroma or not. However it still does smell since YOU are around with (presumably) functional olfactory sense to sense it.

In my mind no. I think about the question assuming that "no one" means no conscious creature with a brain and ears (or variations of ears). Obviously this is an assumption and I know it could never happen in a real world scenario but we need to assume certain things to have a concrete answer to a question like this.

I am not saying that sound waves and vibrations are not created. They certainly are, whether we can perceive them or not. However, different beings can interpret the same sound waves differently; sound is not a constant. In my mind this proves that "sound" is only a label for the way we perceive any given sound wave. There is a flaw in your example about infrared or ultraviolet waves. We know these waves exist just like we know the sound waves exist. Human anatomy does not have any sensory organs for registering these waves so they are not a fair comparison. Again, the I am not debating the existence of sound waves, only the point at which they become what we recognize as "sound".