claping meter

I'm trying to think clapping meter to a public vote.

I started with something simple: An audio input with a conditional to decide what value that triggers a Pusle. Each pulse is added to a counter. The problem is that if the threshold is always higher Pusle does not add to the counter. Example: The audience applauds strong, the threshold is always higher, then just add a few points because the value is always greater than the threshold, this would give a wrong score.

How do I trade values ​​above the threshold to keep counting? any mathematical expression for do this?

any help is welcome.