Tksolfege is an ear training program for learning to recognize chords, intervals, perform rhythm dictation, solfege dictation and singing solfege sequences. The program requires Tcl/Tk 8.5 or higher. Windows executable with Tcl/Tk builtin (starkit) is available on sourceforge.net.
Documentation: https://tksolfege.sourceforge.io/
Source code: https://github.com/sshlien/tksolfege