Detect a specific frequency/tone from raw wave-data

Question

I am reading a raw wave stream coming from the microphone.
(This part works as I can send it to the speaker and get a nice echo.)

For simplicity lets say I want

Answer 1

As far as any .NET libraries that do this try TAPIEx ToneDecoder.Net Component. I use it for detecting DTMF, but it can do custom tones as well.

I know this question is old, but maybe it will save someone else several days of searching and trying out code samples and libraries that just don't work.