Detect Audio "Line In" (mic) audio signal

I currently have a c# windows application. I have an audio line plugged into mic input. I need to detect a signal (it's actually a "beep"). The method (open source) I currently use does not detect 100% of the signal all the time. Sometimes it misses a beep...or falsely detects beep. The beeps could be continuous...but at least 1 second apart. Within this new software, I need a way to define which audio input device to use (as there may be more than one), and the ability to set sample rate and bit depth. I will need a sample c# windows app with code as an example on how to implement. I assume for an experienced c++ programmer and c# programmer......this should be pretty simple. Let me know your price.