Ear Training Resources

A good ear is one of the most important tools that a musician has. Unfortunately, most musicians aren't encouraged to work on ear training skills until they reach college, and by then it is much more difficult to learn. I always encourage young students to work on developing their musical ears from an early age. The resources below are interactive websites where you can train your musical ear for free, provided that you have a sound card, speakers (or headphones), and an internet connection.
1) Teoria - a great interactive website for learning theory and aural skills.
http://www.teoria.com
2) Good Ear - Online Ear Training Site
http://www.good-ear.com
3) Big Ears - the original online ear training site.
http://www.ossmann.com/bigears
4) Earplane - Online Ear Training. Multilingual.