GNU Solfege - free ear training software | Main / GNU Solfege - Smarten your ears
I learnt music sight reading when I was 19. I was a graduate student in Chemical Engineering and I studied in the 15-minutes-break between lessons.
Linear Algebra, then intervals. Calculus, then scales.
They were stressful and consuming years. But I had never regret the time spent on sight reading. Solfege opened the door toward the music I never heard before.
If you're into music in some way, try GNU Solfege. And if you're a musician, even by Schoenberg standards, at least may be good for your disciples.
Comes in Windows and Linux flavors.
P.S.: I will never forget Master Federico Salce, former director of the Cappella Musicale di San Petronio (Bologna, Italy). He taught me sight-singing. He left us four years ago.