Solfege is free music education software.

Use it to train your rhythm, interval, scale and chord skills.
Solfege - Smarten your ears! 

Features
    * Recognise melodic and harmonic intervals
    * Compare interval sizes
    * Sing the intervals the computer asks for
    * Identify chords
    * Sing chords
    * Sing tone from chords: root, third, fifth, etc
    * Scales
    * Dictation
    * Remembering rhythmic patterns 
    * Theory: name intervals and scales
    * Cadences

Notes:

1. If you don't hear any audio, you may have to edit the ~/.solfegerc
   file and add "-Os -o hw:0" to the midi_player_options.
   Mine looks like:

     midi_player_options=-Os -o hw:0 -idqq %s

   I don't see a way to make this change via the GUI.

2. Although freepats is listed as required in the .info file, this
   will work with eawpats instead.