C# WAV file recording from mic and processing WAV file (amplitude, frequency, etc.)

We need a C# client written that will take data from the microphone and store it in a wav file. Then once you have this wav file, we need to analyze it just a little bit. We need to know how much "silence" is in the recording. We are looking for human speech, so we expect to see the amplitude to change in the recording. We need this project completed as soon as possible so please only bid if you have experience doing this.