Pitch detection to find music notes (from voice)
1) Get some practical experience on what you are studying.  By this I mean is take your recordings of your voice and look at them close up on you computer.  You can use a program like Audacity.

2) Yes, you will have to learn about the Discrete Fourier Transform (DFT, the FFT is a computationally efficient version).  I write blog about it explaining it in my own way.  You can find the link on my profile page.

3) Pick a different topic that is worthy of a Master's Thesis.  There are many techniques for pitch determination, which is a pyscho-acoustic phenomenon vs frequency estimation which is basically a physics problem.  Since you are a singer, you might be interested in how sound waves are attenuated as they travel through air.  You simply have to set up some microphones at different distances from the source and look at their waveforms to see what I am talking about.

4) Depending on your math chops, you may consider coming up with data visualization techniques for signal data.  There is lots of room for creativity here.

Hope this helps.

Ced