When a tree falls in the forest, and nobody is around to hear it, I will argue that it does not make a sound. Quickly, I would like to define the word "nobody." For this debate, nobody around should be defined as no living animal within the area in which the tree falling can be heard. The reason that it does not make a sound is simply because a sound must be observed/heard for it to really count as a a sound. Without a brain to receive and interpret the vibrating air molecules, a physical reaction of vibrating molecules is all that will ever happen. A sound is not a sound without an observer. Will the tree have an impact on its surroundings? Yes? Will it make a noise? No.
But just because nothing is around to receive the sound waves does not mean that it does not make a sound. It gives off vibrations in the air, even if nothing living is there to listen to it. There could be gunshots in A different country and we could not be able to hear it, but does it make a sound, yes. Yes it does. It does physically move waves around in the air, so it create some effect in the atmosphere, it affects the air, and thus exists. Not a person, nor living thing needs to listen to a sound for the sound wave to exist.
The example of a gunshot is a good one, but it has a fatal flaw. Just because WE don't hear it, that doesn't mean that nobody hears it. As long as something hear it, it makes a sound. The simple premise of a sound means that it must be observed to exist. You can't have a pretty sight without someone or something to see it, just as you can't have a sound without someone or something to hear it. Without observation, a sound wave is nothing more than a series of vibrating particles no "louder" than than the tree before it fell. Similarly, a massage is just some random person moving their hands without someone to be on the receiving end. The part of a sound that makes it a sound is the sensory organ that picks it up and translates it into a detectable noise. Because we are the ones that define what is loud and what is not, we must be present to determine what is a sound and what is not. Though the vibration undoubtedly exists, it is also undoubtedly not a sound.