I have an application that fills a buffer from my computer's microphone and does an FFT. My objective is to figure out what frequencies are in the sample.
I've tested the application by whistling as well as by playing this video from my cellphone into my computer's mic (I've tried two different mics to be sure). What I expect (taking the absolute frequency) is a smooth Gaussian-like curve with a mean at the frequency of the incoming tone, but what I'm getting is this:
What is the cause for the jaggedness of the signal's frequency spectrum? And what technique can be used to reliably identify the main frequencies present in the signal while filtering out the unwanted bumps?