Yeah I so I downloaded this website to use offline http://www.musictheory.net/. It has been helpful increasing my ability to read music. Recently I started on the ear training portions. I was horrified at how poor I was at identifying intervals. Does my ear suck, or can I, through practice get better. I mean I really sucked. I was even sitting there with my bass playing through the various intervals to help and I could not do it. I know that my does not totally suck, for instance I can immediately tell if I am playing something discordant to whatever chord in being played, but my lack of being able to ID intervals makes me worry.
that's okay man! don't stress too much. not a lot of people are born with a fantastic ear. you just gotta work on it! transcribing songs without using tabs would be the best training exercise. my teacher back then made me transcribe a song per day. do you have a band? filling up your profile will help others give you advice. constant jamming with others and gigging would probably be the best and will really force you to be on your toes. you could also get a teacher or those method books/videos. i watched this one by david gross. he teaches you about identifying intervals by knowing the sound through famous songs (e.g. brahm's lullaby is a minor third).
No one is born knowing this stuff. Practice and experience, that's the ticket. And, as vic says, some intensive transcription really does help, even starting with simple songs whose melodies you know in your head.
Gary Willis has one of the best ear training books for bass players out there. He employs intervals for his particular method, not only ascending intervals, such as root to minor third, but descending intervals such as perfect fifth to minor third. for example. You need to be able to hear and identify intervals both ways. He starts very simply then builds to ever greater complexity. If you procede slowly and diligently through this book and its CD, you should develop a much better understanding of intervals and recognition of them in music you hear or are trying to transcribe. The book is: "Ultimate Ear Training for Guitar and Bass" with CD He has another very helpful book, too, that will also carry you to the enxt level: "Fingerboard Harmony for Bass Guitar" with CD The only caveat I would suggest with either book is that Willis plays his samples and drills rather fast. He probably thinks they are slow, but he is a seasoned veteran. Inexperienced bass players will have to work patiently at the exercises, but if they keep trying, they will be far better off for having done so, even if each book takes a year or more to master.