The Lightbulb Moment: Discovering The Key

Band Performing on Stage

One universally befuddling inquiry is deceivingly simple, “what key are we in?” As easy as it sounds, the key of a song can often be interpreted in different ways, hence making the question a bit more complicated to answer. Are we in major? Minor? Should we be playing to a mode? Do we play “Sweet Home Alabama” in D or G?

Long story short, determining the key of a song is crucial — it helps us identify the chord progression, the chord qualities, and the scales that we can use while improvising a bass line. Defining the key can also be somewhat tricky. It may be the first chord of a song, but by no means is that a rule. The tonal center can also change or modulate as you move through a song… we might have non-diatonic notes, temporary tonicization, and other big theory words that can cause confusion. That said, it’s always a good idea to have some basic theory under your belt to help you understand what a tonal center actually means.

All of the sudden, it seems like there’s an underlying question that needs to be answered before determining the key. Since we all interpret music slightly differently, perhaps we must first ask: “how do I define the key?”

The answer to this question will be based on a few things: how you’ve learned harmony, how you interpret harmony in relation to the music you play, and how the people around you think about harmony. What makes the most sense to you and the people you play with?

For instance, in the “Nashville Number System,” everything is related to the major key. So, if a chord progression goes Bm-A-G throughout the whole song, the progression would be written 6m-5-4 in the key of D Major. In the jazz or classical world, it would be thought of as i-bVII-bVI in the key of B minor. Po-tay-toe, po-tah-toe. Both interpretations are correct, but it’s important to you, as the musician, to ask yourself how you’d prefer to think of the key. This will happen over time; it involves countless experiments in the form of song learning and analysis. As with anything, the more you do it, the easier it will get.

After answering this initial question — how do I define the key? — we need to apply it. There are plenty of occasions when a song starts and the very first note is the root note of the tonic chord. Heck, sometimes that’s the only chord in the song and it’s super easy to say “ah-ha, we’re in E Major!” Or perhaps you realize that yes, we’re playing over an E, but the chord happens to be an E7. In that case, it’s certainly easier to integrate basic knowledge of the modes and consider the key as E Mixolydian. Other times, it can be a bit more difficult to troubleshoot a key center, especially when we’re dealing with a lot of changes. Alas, we’ll need to ask ourselves a few more questions.

One super important (and often overlooked) question is, “have I listened to the song in its entirety?” If the answer is no, then do yourself a favor, put the bass down, and listen. By listening start-to-finish, you’ll have a clearer picture of where the tonal center may be. Sure, it’s great when the first note happens to be the root note of the key we’re in, but songs can often be deceptive. It’s very common for a verse to start on the IV or vi chord, only revealing the tonic when you get to the chorus. Furthermore, there are plenty of songs where the tonic chord isn’t even played (but that doesn’t mean we aren’t in that key). When you listen all the way through, a feeling of resolution or a sense of home may become more apparent. Plus, if you’re trying to learn a song, listen to the whole song!

Once you’ve listened, break it down into sections. Think A-B-A if it’s a jazz tune; verse-chorus-bridge if it’s in the popular realm; 12-bar if it happens to fit a blues form. Determining the sections can also be a great clue to determining the key, especially if the tonic chord doesn’t show up until halfway through the song. If you happen to hear the resolution at the chorus, then try figuring that section out first. It will provide you with perspective and will make it easier to work backwards.

And finally, make sure you acknowledge any suspicious activity, such as non-diatonic chord tones, modulations, or moments of “hmm, that’s interesting.” Who knows, maybe you’ll realize that a verse happens to live in one tonal center while the chorus lives in another. Maybe there’s a “major two” chord instead of the diatonically-correct “minor two.” It’s important to consider how you deal with this suspicious activity… does one note warrant a key change or temporary tonicization? Or is it easier to remember that the whole song is in A major, even though you happen to have a B Major chord in the bridge?

Again, this comes down to asking yourself the right questions when it comes to interpreting — and specifically how you interpret — what is happening in a song. Don’t just flail about, hoping that the notes you play are correct. Take some time, learn some theory, and discover how to ask yourself good questions. That’s always the best way to determine the answer.

Ryan Madora is a professional bass player, author, and educator living in Nashville, TN. In addition to touring and session work, she teaches private lessons and masterclasses to students of all levels. Visit her website to learn more!

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  1. Such a great topic to cover. At times I’ll have trouble identifying the key because a diatonic “rule” is broken. But that section is often what makes the song what it is. Though it’s not easy, I enjoy working though whether the “suspicious activity” is a key change or a brief diversion. Thanks!

    • Mike Brueske

      “Sweet Home Alabama”! My (otherwise very knowledgeable) guitar playing buddy says “G” but I say “D” (because bass players know more about stuff like this)> Now…what about “God Only Knows”…? Discuss. ;-)

  2. Todd

    Great subject matter- thank you Ryan for the insights. Have been working on song-key identification as it relates to bass line creation from a chordal standpoint. This article did provide a “light bulb moment” for me.

  3. Jörg Kutter

    Thanks, Ryan – this is a great topic! As I am also learning to become better at this myself, I wondered whether one would really say that “…the key is E mixolydian”!? Isn’t E mixolydian a mode (the fifth mode) of the A major scale, and thus wouldn’t it be more appropriate to say the key is A major?

    • Hi Jorg, Yes, the E mixolydian mode would then *technically* be the key of A. It’s great that you understand that concept and brought this question up. That said, it’s sometimes easier to just think “oh, I’ll use mixolydian because it clearly has a major third and flat seventh” and think of that as the key. Again, the purpose of this is to marry the theory that you understand with the practical application of it and figuring out how things work for you in an “on the gig” kind of way. Hope this helps and thanks for reading!

      • Jörg Kutter

        Hi Ryan, thanks so much for replying – much appreciated! I guess there is some (unnecessary) confusion because certain terms are used loosely or perhaps “wrongly”, and people don’t always agree on what term to use to describe certain issues. In that light, it is perhaps best to talk about “tonal centers” rather than “keys” in most cases…
        But, I certainly appreciate your motivation to make it all practical in a gig setting where “E mixolydian” certainly conveys more information than “it’s in E” (and also… if you start to discuss tonal centers on stage, the band might quickly look for a replacement bass player ;-)