When talk show bands play an impromptu song, how do instantly play in the same key?

Question

When talk show bands play an impromptu song, how do instantly play in the same key?

In: Other

Answer 1

I used to see this with the Roots a lot during some bits on Fallon. From what I remember, usually just a couple guys start and lay the base and establish the key, then the others can come in and follow from knowing what the key is.

This is a lot how jazz improvisation works too. So long as the key is established either through calling it out or a player playing through it, it’s “easy” from there for others to contribute in musical ways.