Note: I’ve copied this over from my Patreon, mainly as an SEO experiment. These days I’m generally keeping the music-related stuff on YouTube and, to a lesser extent, Patreon, but I want to see whether this post is more “google-able” here or there.
This probably doesn’t warrant a full YouTube video. (Then again, maybe it does, but I have a gig this afternoon and I don’t have time to make one right now!)
The big band I play in (the one that has a gig this afternoon) has “The Chicken” in our books as an encore/jam. I don’t really use the sheet music for it at all because… well, every bass player should know how to play “The Chicken.” It’s just a 12-bar blues in B♭ with a funky groove.
“The Chicken” was written by Pee Wee Ellis when he was in the James Brown band, and was famously covered by the Jaco Pastorius Big Band in the early 1980s. The main part of the song, as I said, is a straightforward blues, but the Jaco recording begins with the “Soul Intro,” a gospel-infused, slow 3/4 intro.
My sheet music has a transcription of what Jaco plays in this intro, and I’ve memorized it, but it always helps to understand the underlying form when I’m going to be playing something like this.
Here’s the part as written (re-engraved by me in MuseScore so I can overlay the chords later; note that I’ve omitted a bunch of articulation marks because they’re not relevant here):

Once you’ve worked out where to play these lines on the fingerboard, this isn’t really that difficult to play. But I find that it’s a lot easier to work out where to play the lines if I understand the underlying chord structure.
I only have two things to go by here: this written out bass part, and the recording. I checked the rest of the books in our band library. I guess there’s no piano part, because the piano player is using the guitar part, and the guitar is just tacet in the intro. There’s also no score, and of course the changes for this wouldn’t be written in the horn parts. So, I’m on my own.
First I tried working out the chords just by looking at the bass part on its own. That got me… pretty close. But then I listened to the recording and tried playing the chords on the keyboard along with the music, and I discovered I was a bit off on a couple of them. (Specifically, it was minor details like treating the opening chord as a B♭Maj7 instead of just B♭, missing a passing ♭VII, not correctly guessing that the part where I’m just playing F octaves is, in fact, an F7sus4… stuff like that.)
Anyway, once I had both examined the written bass part and played my keyboard along with the recording, I came up with the chords shown below. How do you think I did?

To summarize in text, here are the changes as I have them (using percent signs for measure repeats):
B♭ | % | D7 | % |
Gm7 | B♭7/D | C6 | % |
D♭ | % | F7 | % |
G♭6 | % | F7sus4 | % |
% | % | E♭ Gm/D Cm7 | B♭ |
E♭7 | Bb6 ||
I’m still unsure about that 6 on the C6 in bar 7. It sounds weird played on the keyboard, so it’s mainly for the benefit of the bassist.
(Of course, I only noticed after I published this that MuseScore had notated the G♭s as F#s in bars 13 and 14. They’re G♭s in the original.)