rtspeccy is a real time spectrum analyzer. Plug in your microphone and speak, rtspeccy shall visualize your words.

Main features:

• Keep it simple. “It” refers to the code. No complex configuration
  file, simply a config.h.
• Displays the spectrogram using OpenGL.
• Split screen: Show history as well as current spectrum.
  Freeze, zooming and panning.
  
  Overtone guidelines: Click and hold the left mouse button to show
  guidelines which indicate where over- and undertones of the current frequency are located.
  
  History is colored via a color ramp.
  
  Free software (GPL3+).
  
  Files

github.com/vain/rtspeccy