 What I'm about to tell you is going to completely change the way you think about the notes you hear in music forever. Actually come back in here a moment, you may already know about this of course, in which case, meh. So I'm going to start off by playing a single string on my guitar, the A string. Now as you may already know, this string is vibrating between two fixed points, the nut up here and the bridge down here and it's vibrating 110 times per second or at 110 hertz as we say. Let's leave that number up here, we're going to need that later. Now as well as doing this, it's also actually vibrating at twice that rate or frequency at 220 hertz and when it does that, it produces a sound called a harmonic. Now you were largely unaware of that sound when I played the string earlier on. So I've made this clever EQ curve up here to isolate that harmonic so that you can hear it. Let's play the string again. Now it's still the note of A but it's much higher. When we double a frequency we call that an octave. That note of A is one octave higher than the initial note that you were aware of. Now the first sound that was produced at 110 hertz was also a harmonic but we normally refer to it as the fundamental because it's fundamental to the sound of this note and because the second sound that we created was at twice the rate of the fundamental, we call it the second harmonic. It doesn't stop there though. When we played this note earlier, a third sound was created called the third harmonic and that was at three times the rate of the fundamental at 330 hertz. I've also isolated that with this frequency curve so that you can hear it now. Now all of these sounds combined together to create what we call the timbre or timbre or timbre or however you pronounce it in your part of the world, the sound or character of the note that we were playing, the instrument that we were playing it on as well but it doesn't stop there. This phenomena happens naturally and also produces four, fifth, sixth, seventh, etc, etc into infinity harmonics and this series of harmonics which all produce different notes is called the harmonic series. So I must admit when I first heard about this my mind was blown so do me a favor if your mind is blown during the course of this video take a note of what time in the video that happens and put that timestamp in the comments down below for me if for no other reason than to educate me about the lengths I have to go to impress you. Now we're still going to be listening to the guitar sound and we're still going to be playing the note of A but this time on a virtual instrument. Now it's not a fake guitar it's actually a sample or a recording of a real guitar okay and we're going to be looking at this in FAB filter using the spectrum analyzer and as I play this note I want you to take note of the spikes which occur and then gradually die away. Do you see all those spikes there? Let's have a look again. Those are the harmonics which are being produced in the harmonic series. Now as we saw earlier the cool thing we can do is actually filter some of these out so we can just listen to the fundamental or first harmonic which sounds like this. Yep and then we can listen to the second harmonic sounds like that still the same note but an octave higher yeah have a listen again and then we can have a listen to the third harmonic which sounds like this and again. Now I could have gone ahead and filtered out all of the harmonics up through the series but I actually only need the first three right now for a little quiz we're going to do get your ears ready. So there's three parts to this simple quiz and in each part I'm going to be playing one of those harmonics that we isolated with the filter just a moment ago. You won't be able to see which filter I'm using so you'll just have to use your ears but as a quick reminder let's listen to each of those three harmonics so the first harmonic or the fundamental is sounding like this the second like this and the third like this and obviously I'm not going to be using them in that order so let's start off with part one of the test which harmonic am I playing now and again okay part two of the test which harmonic am I playing now and finally part three of the test which harmonic am I playing now now I bet you're feeling pretty smug yeah I bet you feel pretty confident that you got all three of those right especially that last one the really high one yeah it's obviously the third harmonic and you're right it is the third harmonic but I'm afraid to say I tricked you because it isn't the third harmonic of the guitar anymore instead it's the third harmonic of this the same note but on a piano and that's because all pitched instruments produce the same harmonics from the harmonic series let's dive into that a little bit further so now I've got three instruments loaded up the guitar the piano and a cello now if I isolate say this time the third harmonic with each of those we can listen to the guitar the piano and the cello and you'll notice they all sound pretty much the same one of the minor differences is to do with the attack and decay times obviously some instruments have a much sharper attack like the guitar and the piano and some a slur attack like the cello here and the decay times are different as well but they still share the same harmonics as you heard there with the third harmonic but these are all stringed instruments what about wind instruments for example well let's have a listen to these two and this one the first one there's actually a tuba and the second one a bassoon and yet they still share the same harmonics from the harmonic series that the stringed instruments did so you may ask well if they all share the same harmonics then why don't they actually sound the same and the answer to that is is that they all share the same harmonics but at different levels okay let's have a look at some of these have a look at the guitar you can see a lot of the lower harmonics are a lot louder there with the guitar and if we compare that to the bassoon you can see those middle harmonics are much louder than the fundamental even yeah have a look again and it's this sort of combination of the harmonics at different levels which really contribute to the sound of the instrument let's explore this a little bit further using a synth so using something called additive synthesis we're going to create our own timbre by generating harmonics on top of a fundamental okay and for this I'm using pigments from Arturia so we're going to start off with the fundamental this time it's going to be the note of C we can hear that sine wave there and using this control here we can add in harmonics from the harmonic series or as they're sometimes called like they are here partials okay so let's just gradually add a few in and listen to the sound and how it changes and did you notice there as I add them in they actually form the sound of a C major chord or just any major chord okay have a listen again I'm just going to add in those first six and although you can hear the individual notes of that chord when I go ahead and actually use this sound on the synthesizer for a melody you're no longer aware of that kind of chord which is created by the harmonics and you're mostly focused on the fundamental your brain identifies the note mostly according to the fundamental okay so let's go ahead and add some more partials so I've added a few more there they're no longer forming a major chord okay and you'll notice they're getting closer and closer together we'll add a few more and the higher we get and the closer they get together the more kind of harsh the sound becomes okay so that's the basis of adding those partials or or harmonics here but let's just mess around with the distribution a little bit okay I'm going to start off by using this tilt control here what we're going to do with that is make some of those higher harmonics a little bit quieter and you'll notice although they're still present the sound has a much softer kind of tone to it okay if we make them louder again we've got that sort of harder tone now we're sort of adjusting them across the range there but we can sort of notch out a few of them using some filters with this synthesis I've prepared a filter here I'm going to use this depth control to gradually fade it in and you'll see that the distribution changes again a little bit here have a listen to the sound yeah here I'm kind of knocking out some of the alternate harmonics which are being created and as you can see this forms the basis of the timbre of our instruments some instruments like percussive instruments don't necessarily make use of the harmonic series in the same way as the pitched instruments that we looked at today as well as this some of the notes which are produced in the harmonic series don't quite line up in terms of frequency with the notes we normally use in the 12 equal temperament system that we generally use in western music to find out more about this I've provided some links in the description down below so that you can do some further reading now harmonics are also naturally produced in some of the hardware that we use in the studio to find out more about that I think you should watch this video right here