For some time now I have been spending some of my practice time trying to improve my ears. I've been using the Interval Ear trainer at www.musictheory.net and I don't think that I'm doing that much progress. I've been sitting with my bass and playing different intervals in all keys (mainly 3rds and 4ths) trying to get my ear accustomed to the different intervals but I'm not really making any progress as far as I am concerned. So, now I am wondering if there is a correct way of practicing your ear, since this is getting quite frustrating. Any and all tips are welcome! Thanks!