I'm just "thinking" about the vocoder, because I saw somebody use it and it sounded cool (for their voice). The vocoder needs an additional signal that it uses to create the harmonies with your voice. I saw a guy use his keyboard (typical) but you could probably use your bass if you wanted to.
I'm sure it's just some passing GAS, since I'm not much of a singer
I'm sure it's just some passing GAS, since I'm not much of a singer