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How to find the tonality of any song

How do you find the key of a song? Has it ever occured to you that you want to play a tune with harmonica, guitar, or any other instrument, and don't know where to start from? In this article I'll teach you a quick way to figure out key of any song in a few seconds and also to choose the right harmonica for playing it.

To learn about the musical tonality of a song we need to understand a few elementary notions of musical theory first, but above all, we have to debunk a myth: the first and the last chord of a song don't show the key. It happens quite often that you hear someone saying so but it's incorrect. If you trust this method you will never be sure of the result. I will not go into detail as why such is the case, but you only need to perceive that; e.g. in a major C key we find also minor chords, such as E minor and A minor. If a song starts with a minor E chord, it could be a E minor tune but also a C major tune.

Let's go back to our method:

First of all, we need to familiarize with what actually a musical interval is and I'll explain this as the distance between two notes. For instance, if I play a C followed by an E, this interval would be called a major third. If we take the C major scale, we have in fact the notes C, D, E, F, G, A, B; counting from C, we have C, D and E.

Let's take another example, if we p1ay an E and then an A, we count E, F, G and A: i.e. the musical interval is 'fourth'.

What is the point in understanding the musical intervals? It is immediately told that there is a very important interval that is the third one which determines the mode of a scale as well as mode of a chord also, and it goes in the same way for the entire song. I'm sure you must have heard of a minor or a major song; that's the source where this definition comes from.

What determines whether a chord, scale or song mode is a major or minor one? Just the third interval! If the third interval is 4 semitones away then the mode is major, if this interval is only 3 semitones apart, the interval is minor. To give an example, C followed by E is a major third interval, C followed by an E flat is a minor third interval.

If we apply this notion to a chord, we have that C-E-G as a major chord, while C-Eb-G as a minor chord.

Similarly if we take a musical scale formed by the notes C, D, E, F, G, A, B; it is a major scale and if we consider the set containing C, D, Eb, F, G, A, Bb; the scale would be minor.

Let's see how we can use these notions to find the key of any song. For this purpose, we simply perform the following steps:

1. We play the song and with a C melody instrument, we look for the note that sounds good through out the harmonic progression of the song itself. We can use a piano, a guitar or our 'harmonica'. The right note is identified as the one that always gives us the feeling of being in the right place even when the chords of the song do change. To perform this test, we need to be able to produce notes chromatically, which means to play all 12 semitones of an octave. In the case of a piano, we play all the black and white keys one by one in a sequence to achieve the desired output. If we use a harmonica - this process is a little more complex - to play it chromatically, therefore, we have to use bending. A harmonica player with a trained ear and knowledge to play the bending manages to find the note ultimately and with great ease too.

2. Once we figure out the 'home' note, this would be the one that gives the name to the song key. Now we need to find out if the song is in minor or major one. An experienced ear would recognize it without further passages, given that the minor mode is characterized by that sad and melancholy 'taste', while the major mode is more cheerful. But we want a functional and safe method too, therefore, we'll analyze the interval of third to see if it is minor or major. To do this, we will play the interval of major third two or three times, and then we will try the minor third while the song is still playing. We will notice right away which interval works, because the wrong one will sound really out of place! Once we find the right interval, we will spot the song's key in no time!

Let us now give an example to review the concepts we just explored:

Suppose a song is playing: let's start playing the notes C, C#, D, and we realize that D sounds pretty good. We continue with all the other semitones to make sure that there is no other note that sounds better than D.

When we have established that D is the best note, we know that the song is in D. At this point, always when the song is still playing, we'll play D and F sharp twice or thrice in a sequence. If they sound good we are in D major but if they sound bad, we'll play D and natural F and if this interval sounds really good then we are in D minor!

See how easy it is? Now you can find the key of a song in less than 30 seconds.

To choose an appropriate harmonica, with which to perform this, you just have to decide in which position you want to play and it's all done. If the song is major; you could use the first position or the second, whereas for a minor tune, you can orient yourself on positions three or five instead. Good music!


If you want to comment this lesson use the contact form available here.

Marcy Ludwin
Clear, precise and understandable lesson. I can play the harmonica, have been playing for many years; however, your lesson here is wonderful for those who may be starting now or who want to better their playing. Finding the key of a song with this method is really fast!

Fred Banfield
Hey man! This was so useful! I'm a guitar player expanding my instruments I play. So from Cigar box guitar to the Harp was just a natural thing and you’ve made it easy to understand and get into. Thanks a stack and keep bringing the lessons like this one. It is true, the first chord of a song is not the song key!

Kira Martinez
Your lessons are clear and full of great information, I am getting a new harmonica (Hohner golden melody), and I'm pretty sure your lessons will be useful. Thank you for all the information you share on this website too.  - Privacy and Cookie Policy