How to covert hummming into pitches?
You can try using a Pitch Track for monophonic signal, you need track low pitches!

There is a wide range of algorithms to find Pitches in time domain (zero crossing, AMDF, YIN, MPM, ASDF, autocorrelation ....) or Frequency domain (shs, hps, cepstrum ....)

Each one of them possess advantages or disadvantages !

With the Pitch Track you can convert one frequency to note.

I never used Flash AS3 to DSP, one fast and easy way are the autocorrelation based algorithms.