Capture Sound from Mic/Headphone and trigger action at perticular frequency

I am using .NET 3.5.

I need to Capture Sound from Mic/Headphone and trigger action at particular (not exact) frequency (Need to perform some action when player hits ball with stick 开发者_开发问答while playing golf).

So,

1. How to capture sound from Mic/Headphone using .NET 3.5?

2. Trigger action at particular (not exact) frequency?

Any ideas?

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For (2) I suggest the Goertzel algorithm, which is very simple to implement and will allow you to detect energy in a narrow range of frequencies.