possibilty of extracting a tone from MIDI values

Question

I have a project of recording human's sound via Android's SoundRecoder API, and then displaying the extracted note on The screen. It is specific for Android platform (can't use Jmusic or Jfugue API as javaSE environment is not supported).

Now suppose I get to record a sound using this API . How can I then deploy FFT to extract notes from this sound? Basically as it is not pure sinusoidal wave it might involve multiple frequencies and overtones. Are there any good algorithms to do so? If yes, where I can simulate and the last of all whole of the extracted tone should be rendered on musical sheet?

Answer 1

You correctly note that a musical note is usually not just a simple sine wave. Thus, an FFT may only be one of the steps used in a pitch detection/estimation algorithm (there are many: http://en.m.wikipedia.org/wiki/Pitch_detection). For music, a good place to start might be the research papers published on MIREX: http://www.music-ir.org/mirex/wiki/Audio_Melody_Extraction

Answer 2

A simple way is to search for the maximum amplitude in the spectrum ; however depending on the instrument this could either be located at the fundamental frequency or at a multiple of that frequency, so what you could do is extract these frequencies and their harmonics along with the associated amplitudes, and correlate the data against sample values for different instruments to identify the note played (and even the instrument)