I am currently learning to play the guitar, and that has sparked an interest in learning more about music in general. I would like to learn about music theory, ear training, history, musical styles and forms, ethnomusicology, and the like.
When learning about music, I find it best to be able to hear what is being discussed. In addition, I commute to work via the subway, so I have about half an hour each way that I could be listening to lectures and examples.
Are there any good resources of podcasts or audio lectures, either free or for purchase, that I could download and listen to on my commute to learn more about music?