Ask HN:where can I find audio courses?

Well you may be wondering why I would like courses in audio format if I can have a good set of video lectures of most topics.Here are my reasons: 1)I don't own a fancy iPod or any video player.I just have a good philips mp3 plyaer (go gear series).Which I like and is all I can afford.Don't even think about mentioning my cellphone as its a very funtional one,no multimedia in it. 2)Easy to download.They are like 15-16 or at the most 25Mb and a very quick download.Video lecture take 5x the time,besides I prefer streaming videos rather than download it. 3)Thats all I can concentrate on, while on the college bus.I travel for like 1 1/2 hrs up down (totaling to 3 hrs of wasted time listening to songs).Even if I had a fairly decent video player, I couldn't even begin to concentrate on the 3-4 inch screen.Its just too small for me. I searched the internet and interesting (to me) course I found in audio where Game theory at open yale project[1].Thats about it. So I ask HN, do any of you use such things?Can anyone give me good links to other open audio courses. My interests are mainly in electronics and mathematics.