There is also an optional Pitch detection plug-in available here: http://wiki.audacityteam.org/wiki/Nyquist_Analyze_Plug-ins#Pitch_Detect
Again it can only detect the pitch for single notes, but in tests it has shown to be pretty accurate.
More information about this plug-in here: https://forum.audacityteam.org/t/pitch-detection-plug-in/29126/1
Installation instructions: http://manual.audacityteam.org/man/effect_menu.html#nyquist_effects