Artificial Harmonics
Artificial Harmonics are a way to get harmonic resonance from a string while it is fretted. Like natural (open string) harmonics, artificial harmonics involve dividing the string into an integer multiple of separate resonating pieces, by placing a finger on one of the pivot points or "dead spots" and sounding the string. The big difference is that since our left-hand is busy fretting the note, we have to use the right hand to do so.
Artificial harmonics are usually indicated by a * before or after the fret number. Sometimes the actual pitch of the sounded note is written above the tab. And sometimes the * is simply above the tab.
E * E--<5>--*12--12--[12]-
The above is a natural harmonic created by using the left-hand as a pivot above the 5th fret. The next note involve actually fretting the 12th fret, but using an artificial harmonic to get that same note. We are given the actual pitch that should be sounded's note name, but we don't know exactly which harmonic this is. It could be the 2nd, 4th, or higher. The final note is an ambiguous artifical harmonic - we know we are getting a harmonic of the 12th fret E note, but we don't have any information about which harmonic to sound.
The way artificial harmonics are executed using the right hand thumb usually means the harmonic sounded is the 4th, 5th, or 6th harmonic, which is going to be very high-pitched compared to non-harmonic notes played at the same location on the left-hand. For this reason, they are often called squeals or squealies.
Contents
PreReqs
Picking Technique (Pinch Harmonics)
This is what is most commonly referred to when saying "artificial harmonic". This technique uses a slighted tilted picking hand to allow the thumb to touch the string as the pick plucks it. The thumb acts as a pivot point to create the harmonic, just like the left-hand finger for a natural harmonic. And again like natural harmonics, you want to lift the thumb off the string as soon as the harmonic is sounded. Usually it's just a normal picking motion, but you add the thumb.
It is possible to use your right hand index finger (or another finger) as the pivot point; however, I find this is more difficult. For my pick grip, my index finger's nail would likely touch the string, which doesn't work as well as the flesh of the side of my thumb.
For this technique to work correctly, you must focus on pressure, timing, and accuracy. You must use enough right hand thumb pressure on the string to deaden that point on the string but not so much that you end up muting the string instead of simply deadening the pivot point. Your thumb must touch the string at the appropriate time - right before the pick plucks the string or right after (basically at the exact same time), and it must be pulled off the string as soon as possible after plucking the string with the pick. Finally, the location of your right thumb (the pivot point) must be correct. This will depend both on which harmonic you are trying to sound, as well as what fret your left hand is fretting.
This technique is often called a pinch harmonic because the picking motion feels similar to trying to pinch the string.
Beginner Excercises
3rd harmonic ---<7>---<19>----[0]--- 4th harmonic ---<5>---<24>----[0]---- 5th harmonic ---<3.8>---<32?>---[0]--- 6th harmonic ---<3.2>---<45?>---[0]--- 7th harmonic ---<2.6>---<65?>---[0]---
First we need to practice getting the motion down, and locating the pivot points for open strings. The fret numbers inside <>'s are natural harmonics. Notice how each line has two natural harmonics, then an open-string artificial harmonic. All 3 pitches should be identical.
The first two examples have fret numbers for the 2nd natural harmonic. If you measure the distance from the nut to the 7th fret, this is the same amount of distance as the bridge to the 19th fret. Same thing for the nut to 5th fret and bridge to 24th fret. Remember that a harmonic has the string resonate in equally-sized chunks on the string, divided by pivot points. The distance from the nut to the first pivot point is the exact same distance as the bridge to the last pivot point.
Once we find the closest pivot point to the bridge, we know where to apply our thumb for the artificial harmonic. So in the first two examples, your thumb should touch against the string above the 19th and 24th frets, while your pick strikes the string slightly closer to the bridge. These are the best places to practice the actual artificial harmonic picking stroke. Your artificial harmonic should sound almost identical to a properly-played natural harmonic. The pitch should be pure, not the open-string pitch plus a slight harmonic pitch. It will take quite a bit of practice to get this to start sounding right, and even more practice to get it consistent.
Once you have the stroke working well, let's move to the 5th, 6th, and 7th harmonics. For these, the last pivot point is not over the fretboard, so it is basically impossible to list exactly where it is without getting a ruler and taking an actual distance measurement (but even this will change if your instrument has a different scale). My advice is to sound the natural harmonic on the nut side, then lightly press your left hand finger against the string near the bridge like you are trying to sound a natural harmonic. Keep picking the string with the right hand (you may have to pick over the fretboard, so your hands are criss-crossed), while you slide the left hand finger towards the string. You should hear a bunch of muted thumps and occasionally some harmonic pitches. Stop when you hear a pitch that matches the one you are trying to find. It should be the same distance from the bridge as the nut to the fret listed above.
Once you've found the correct distance, try making the open-string artificial harmonic, with your thumb touching that pivot point. You should be able to sound the 2nd, 3rd, 4th, 5th, and 6th harmonics using artificial harmonics.
Notice the position of the natural harmonics from 3rd to 7th: 7, 5, 3.8, 3.2, and 2.6. The higher the harmonics go, the closer together their pivot points occur on the fretboard. Try to sound the same artificial harmonics:
Harmonic: 3rd 4th 5th 6th 7th 3rd 4th 5th 6th 7th
Tab: --<7>-<5>-<3.8>-<3.2>-<2.6>----[0]--[0]--[0]--[0]--[0]-
pivot towards bridge ->
Notice how just as you move your left-hand closer and closer to the nut but in increasingly smaller distances for the natural harmonics, you also move your right hand closer and closer to the bridge in increasingly smaller distances for the artificial harmonics. Physically speaking, natural and artificial harmonics are the same thing - only the technique used to create them is different.
Now, we get to the tricky part. When you fret the string, you shorten the resonant portion of it. This means that the resonant divisions of the string for a harmonic have been shortened as well. Let's take a simple example to illustrate:
2nd 4th 2nd 4th e--0--<12>--<24>--12--[12]-[12]--
First we have the open E string, then its 2nd harmonic, then its 4th harmonic (using the last pivot point at the 24th fret rather than the first at the 5th fret). The pitches played should be the open-string E4, its octave E5, and the next octave E6. Then we play the 12th fret and sound the 2nd and 4th harmonic using artificial harmonics. These pitches are E5, E6, and E7. We keep the 12th fret held with the left hand. The pivot points each shift halfway closer to the bridge. For the 2nd harmonic, the pivot point moves from 12th fret to 24th. Just like the 12th fret cuts the open string in half, the 24th fret cuts the portion of the string from the 12th fret to the bridge in half. For the 4th harmonic, the pivot point will be halfway between the 24th fret and the bridge. The notes should be all one octave higher, so all 6 notes are: E4, E5, E6...E5, E6, E7.
This should plainly illustrate how fretted notes shift pivot points; however, it's a very academic example, where everything is either cut in half or doubled. Let's look at a messier example:
4th 4th e--0--<5>--3--[3]--
String length and pitch are inversely proportional. The third fret G is 15/12ths higher pitched than the open string E. The distance from the 3rd fret to bridge is ~12/15ths the distance from the nut to the bridge. This means all the last pivot points (those closest to the bridge) for harmonics are now 12/15ths their open-string distances as well. In other words, you need to move your right hand 3/15ths closer to the bridge to maintain the same pivot points.
4 4 4 4 4 4 4 e--[1]-[2]-[3]-[4]-[3]-[2]-[1]--
Here we're just moving up and down chromatically. This illustrates the necessity of moving the right hand pivot point to match the left hand fret.
Let's get fancy:
4 5 6 5 4 4 4 5 6 5 4 4 4 e--[1]-[1]-[1]-[1]-[1]-[2]-[3]-[3]-[3]-[3]-[3]-[2]-[1]-
Now we are practicing holding the fret constant and changing the harmonic achieved, as well as changing the fret while keeping the harmonic order constant.
Common Issues
Most players don't bother to worry about which harmonic they're getting (and in turn what note they're actually playing). They just "pinch and pray" - they fret the left hand note, use the pinch harmonic picking motion, and hope to get lucky and land on a harmonic pivot point. In my experience, this is about a 50/50 shot, at best. 50% of the time you will not hit a good pivot point, leaving yourself with a muted thud instead of an epic squeal.
Honestly, truly mastering pinch harmonics for the entire fretboard is very time-consuming. Instead, my advice is to get accustomed to finding the 5th and 6th order harmonics for frets 2-5. This is where they are most usually incorporated. As you get higher up the fretboard, pinch harmonics tend to be used less. At the same time the pivot points tend to all fall into a smaller and smaller length of string over the bridge pickup; so you are more likely to "get lucky".
The most common point of failure is a bad picking hand technique. Either there's not enough or too much thumb pressure, or the timing is off with the thumb contact being removed before the string is picked. Sometimes, the thumb touches too "wide" of an area on the string, extending too far from the pivot point and muting the string.
Sometimes the pick and thumb are both touching the same point, which means that the thumb isn't on a pivot point, or the pick is plucking a pivot point. The pivot point is dead - plucking the string here will not produce any sound. For example:
pluck string exactly over 12th or 24th fret. e--<5>--
This will not make any sound. Now try plucking the string at the 17th fret, or behind the neck pickup. Now it sounds. You can't pluck a pivot point and get a harmonic.
The pick must pluck the string in a slightly different location than the thumb is used to create a pivot point.
Artificial harmonics are by nature very weak in volume, particularly as you use higher and higher harmonic orders (particularly 6th or 7th orders). If not using compression/distortion, it can be difficult to hear them at all. Lack of compression/distortion shouldn't be assumed as bad technique; however, the notes should still be audible on an acoustic guitar if you have good technique.
Tapping Technique
This technique uses tapping instead of picking. Unlike normal tapping, where the right-hand is actually fretting the string and holding that note for a duration, here the right hand simply taps the string against a fret to cause it to sound but is immediately removed from the string. That means you tap the string directly over the fret (like the position used for a natural harmonic), not slightly behind it like you would if you were actually fretting it. However, unlike natural harmonics, you are actually pressing the string down and touching it against the fret for an instant. The idea isn't to hold the string against the fret, but to use the metal (string) against metal (fret) contact to cause the string to vibrate then remove the right hand entirely and let it vibrate.
You tap the frets usually one octave above whatever notes the left-hand is fretting. So for instance, if you are fretting the 2nd fret with the left hand, you'd tap against the 14th fret with the right hand. The result is that you get the 2nd order harmonic (one octave higher) for the fretted note.
The basic effect of this technique is much different than when using the picking technique. The picking technique usually generates higher order harmonics that really stand out, useful to emphasize a particular note in a riff or solo. This technique is more often used to give arpeggiated chords a chime-like sound.
E-----------2(14)-- B---------2(14)---- G-------3(15)------ D-----4(16)-------- A---4(16)---------- E-2(14)------------
Tab with artificial harmonics via tapping usually look something like the above - the first number indicates the left-hand fret, while the number in ()'s indicates the fret number to tap to sound the harmonic. Remember, the tap isn't designed to actually fret the note in ()'s, but to simply tap the string into the top of that fret, causing the string to sound.