Is there some possibility to generate sounds in C#? I mean not just beep or open and play wave-file. I mean build the signal using different kinds of waves (sin, saw, etc.)
Here's a blog post I wrote about how to create a sine wave with NAudio. Obviously that's just a first step to making a full blown synthesizer as you will also want to create other waveforms, ADSR envelopes, filters etc, but it should at least get you started.