I overheard a precocious child asking his mother this question on the subway. For him, it was resolved: yes, because the event produces soundwaves that are emitted regardless of whether someone has heard them.
My favorite version of this question is:
Does a work of art lying in the bottom of the ocean continue to be a work of art? (Schelling)
Or:
Does a blog that no one reads and contributes to continue to be a blog?
