The mic is the most critical part of the system. You are trying to "hear" the difference between "tics and tocs" @ 28800bph I guess you need a good mic to capture the "tics and tocs" and not the ambient noise.
Clock movement "tics and tocs" are louder than your wristwatch "tics and tocs". There are a few mic recomendations at the site.
Please let us know the results.