Years ago I wrote the following article: https://channel9.msdn.com/coding4fun/articles/Generating-Sound-Waves-with-C-Wave-Oscillators
I lost all of the source code for it - I think - but this probably contains something very similar.
It's built for Windows Phone 7. Between WP7 and Zune I have enough dead content to raise a zombie army. Accordingly, perhaps just look at the code and see if you can incorporate it into your own projects.
I truly hope this is useful. If I ever find the "real" source, I will upload it here too.
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