How do time and sound change for the man as the moment of his hanging nears?

In “An Occurrence at Owl Creek Bridge,” as the moment where the floor beneath him is about to give way, time and sound seem to slow down.  This can be determined to be the case because within the time span of only a few moments, the protagonist is able to mentally have an entire adventure that includes him escaping before he is taken back to the make-shift gallows on the bridge and he is hanged.