Listening skills for a musician are crucial. A lot of training to be found online involves simple interval identification and chord-type identification. This is great, but the musical contexts in which these musical events happen are also (perhaps even more) important.
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Gil DeBenedetti has created some fantastic resources for just this kind of contextual ear-training. It uses classical music as its material, which is great, and it would be fantastic to see this for jazz, too. Anyway, hear you go 🙂