Matching vocals to chords

[paniak17]

ok ill try to explain to the best of my ability, well say i have a vocal line in my head and can play it from scratch without learning it. whenever i do that its in the wrong key and all i have to do is shift up a couple of notes or something. How can i improve my hearing and not mess up like that. More importantly, if you have a vocal line, how do you determine the chords? thanks for the help.

[RicPlaya]

Work it out on a keyboard or piano so you can see the notes the vocals are making then duplicate it on your bass or come up with basslines that support it.