I can pick up songs on guitar, piano, drums, all by ear. My voice is getting better, lots of control and am figuring out what style fits me best. But now I'm ready for a challenge, I try singing the harmonies on the songs I practice but it's tough. Alice in chains, def leppard, I can't sing a new tone over one I'm hearing. But if I could figure out exactly what intervals are being used in sounds I enjoy, I can practice. I just haven't found any breakdown of these songs explaining what's going on theory wise and my ears definitely need training. Take any def leppard song really, I'm assuming it's big intervals like fifths and octaves to get that airy sound, but I don't know. Do you practice by just going for it? Or would you do it more logically, play a tone and try to harmonize a specific interval over it? I know how they produce and mix for that specific style, tons of reverb, tons of layers, it's recording and singing them that I find trouble in.