comes down to how you define "sound". As a sense it wouldn't exist if noone is around to hear it. But as a wave it would exist, because physics
If you consult Merriam-Webster, it seems merrak is correct:
Definition of sound (Entry 1 of 7)
1a : a particular auditory impression
1b : the sensation perceived by the sense of hearing
1c : mechanical radiant energy that is transmitted by longitudinal pressure waves in a material medium (such as air) and is the objective cause of hearing
1a and 1b indicate that there must be an eardrum present for sound to exist.
1c indicates that there merely needs to be pressure waves present for sound to exist.
It seems that until we can get our act together, and we can agree on one definition of sound, it's impossible to solve the thought exercise definitively. Good discussion for insomniacs. Haven't seen Winnie the Pooh yet, but I've seen tracks and scat, and heard his mating call.