The answer is infinity. Sound doesnt just circle the globe, it travels up and beyond thru space and time. And the farther away, the older the sounds. Somewhere far out in the vastness of space, dinosaur roars are still travelling. A body ( or sound) in motion continues in motion unless something stops it.
What fucks with me is that, if we see a star 2 lightyears away explode, we are looking back in time, because the light of that explosion took years and years to reach us. The big Ear in Puerto Rico hears space sounds alll the time and noises from other galaxies, etc...
I dont remember who quoted it, but it says we are all just a mechanism striking a chord upon an infinite instrument.
Our senses are nothing but delicate readers of electrical impulses that our minds percieve to interpret...its amazing.