The Diligent Musician‘s The Jazz VP talks about why, how & what to learn by ear as well as talk importance of transcription. He recommends Anytune and transcription if you want to learn how to improvise, master the language of music, to help you sharpen your ear, and to reinforce or develop your sight reading abilities.
I personally recommend Anytune. [Anytune has] great sound quality when you slow down music, can easily loop, EQ. I use Anytune Pro+ on my iPad when I’m not in front of my computer and for the wonderful bookmarking feature and cloud backup.
So go checkout Learning by Ear – Transcription Primer