Ear Training
What can I do to improve my ear training? I've played instruments for two decades; it seems to have had little effect because I had to start ear training at square one. I practice and practice, but I cannot get the sound of the intervals to stick in my head. I even sometimes mess up easy ones like octaves. The practice seems to make it temporarily a bit worse, because the more intervals I listen to in a short period of time, the more all the notes begin to rush together and sound the same. This is how I end up mistaking an octave for a smaller interval.
The only ones I'm consistently good at are perfect fourth, perfect fifth, major third, and unison. I have memorized the color or feel or tonal quality of these. I have to stop and think about major second. All the others sound/feel generic to me; I can't pick out a unique tonal "flavor." I've listened to a single interval over and over again but I don't really feel it. They're just random sounds.
And is it really impossible to learn perfect pitch? Or simply incredibly difficult?