Music Theory: Introduction to Minor and Major Thirds

Last week, you met the minor second (also called a half step) and the major second (the whole step). The joy of intervals is that guessing them from here on out is often impossible, frequently frustrating, and downright dangerous. Well, except for right now: if you guessed that minor and major thirds are next then ding, ding, ding, we have a winner!

The process for finding these new intervals is simple as a baked pastry. From our whole step (made of two half steps, if you recall), we walk up one half step and there we have it, our minor third. For those of you who have done the math, yes, the minor third is three half steps, and yes, that is the last time the number of half steps will ever line up with the name of the interval. Prepare to be disappointed.

Immediately following the minor third is the major third with a distance of four half steps. Finding out a major third has four half steps can feel like realizing 57 is divisible by 19—you may need a minute to process. As frustrating as this can be, the fundamental concept is still the same: major intervals are always larger than minor intervals. We must always keep this in mind, somewhere beside the ever-haunting image of 19 x 3. 

At this point, you may be asking yourself, “Hey, what about musical examples like the minor second being the Jaws theme or the major second being the start of Happy Birthday?” Good question, but please stop rushing me.

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At this point, you may be asking yourself, “Hey, what about musical examples like the minor second being the Jaws theme or the major second being the start of Happy Birthday?” Good question, but please stop rushing me.

Thirds are perhaps the most ubiquitous interval found in popular music. Ever heard two people harmonizing closely with one another? Chances are those are thirds. Ever heard someone strum a chord on the guitar? Those are built mostly of thirds. Okay, okay, relax, I’ll give you a good melodic example (what did I say about rushing me?). 

If you don’t mind, sing the chorus of the Beatles’ beloved “Ob-La-Di.” Now just sing the initial ob-la-di. What you’ve found are ascending thirds (which, we’ll discover later, form a chord). Now just sing the ob-la. There’s a major third—simple as that! Now try just the la-di. There’s your minor third! Without knowing it, you’ve had thirds in your bones since history’s very first Ob. It can be helpful to have another minor third example that’s not contextualized by a major third. For this, a common trick is to use the first two notes of Deep Purple’s “Smoke on the Water” riff.

But wait—what if you have a listening age that’s younger than seventy? Here are some examples just for you. For the minor third, harken back to Katy Perry’s smash hit “Firework” (I may be inadvertently dating myself by calling this modern, but never mind that). Sing the line “Do you ever feel like a plastic bag…” Now, isolate the “Do you.” There’s your minor third! For the major third, set your pop music mind aside and pull out that timeless favorite “When the Saints Go Marching In.” The first two notes (on the “Oh, when”) form a major third.

Alrighty, enough numbers and noises for today! Thanks for keeping up with us on this series. Next week, you’ll be able to peruse a growing ear-training chart of song references, so keep an eye out for that. Have a happy time humming intervals all week!

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