DirectX (DirectSound) should be a good solution for WindowXP. You need to create a Filter (see the examples of DirectX, there are a couple of filter examples) and then make sure sounds are being played using a graph that includes your filter.
Your filter must then provide information about fequencies and strength.
Some filter examples :
http://msdn.microsoft.com/en-us/library/windows/desktop/dd375468(v=vs.85).aspx[
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See the 'Scope Filter Example' which is a WaveForm representation of your sound, which comes close to what you want.
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