"Does the moon exist if no one is looking at it?" ... a question posed by Einstein to Niels Bohr. From a purely scientific standpoint, sound is a hearable noise not necessarily a noise that is heard. But if the definition is shifted so that only the perception of the noise qualifies it as sound then no, the falling tree does not make sound.
The question of whether an event takes place without some type of observation by an actor becomes even deeper when asked within the context of quantum physics, since the presence of an observer has been proven to alter the very state of a thing.
So I guess it can be argued that an individual's rights are dependent both on the definition of "rights" as well as whose perspective they are viewed from. But I put forth that the Founders' insistence that rights are natural and inalienable was meant both as a way to rail against oppression as well as the very foundation stone that made the new Republic a great step forward. Now if we can only keep it. Even if we don't, I will maintain that I have my rights even though I be prevented from enjoying them. The tyrant's denial of my rights be damned. That was somewhat hyperbolic.