A natural harmonic is the most common one. Someone will call them “open string harmonics” because you don’t contact a string with a fret while you are playing it - you just have to quickly touch a string above a fret. Depending on a fret, you will get a sound related to the string tone (when you pluck a string with no fret pressed). The tone results in a clear crystal-like sound.
| Fret || Interval ||like pressed on fret
| 12 || octave || 12
| 5 || double-octave || 24
| 7 || fifth in octave || 12+7 = 19
| 9 || major third in double-octave || 24+4 = 28
| 4 || major third in double-octave || 24+4 = 28
| 3 || fifth in double-octave || 24+7 = 31
You can also get the same harmonics on the 16th, 19th, 24th fret etc.
Here is example for the standard tunning (image taken from www.guitarlessonworld.com ):
If you are using high gain, you may hear even some more complex harmonics on some positions, but TuxGuitar doesn’t support those natural harmonics.
Read more about natural harmonics.
Artificial harmonic has similarity with natural harmonic, but is done by pressing a string: you press a string on wanted fret, place a finger (usually your index finger on the right hand) on specific location and then pluck the string. The specific location is some ratio of the strings’ length between the pressed fret and the rest of the string. Usual ratio’s are 1/2, 1/3, 1/4 etc. If you put your index finger 12 frets ahead the pressed fret, you will get an octave tone (like 12-fret natural harmonics).
It is maybe a technique difficult to master, but surely usefull.
In TuxGuitar you specify an artificial harmonic by specifying a “fret offset” between original note and a harmonic hot-spot (where place a finger of your picking hand). It means if you want a double-octave harmonic on the 11th fret, you should enter fret 11 in the tab and apply A.H(5) harmonics effect.
Read more about artificial harmonics on Wikipedia, or see an example video on YouTube.
Pinched harmonics are basically very similar to artificial harmonics, but the way they are carried out is a bit different. Their use is also different, because they are most often played on electric guitar using distortion, which amplifies harmonic effect, and a pick. Pinched harmonics are played by pressing a fret with your left hand, but the right hand does the trick: when plucking a string (with a pick) your thumb (or any other finger?) should simultaneously after-touch the string and make the harmonic on the place you plucked the string.
It is hard to explain, but not very hard to do: it is all about placing your picking thumb properly. It can get complicated if you want to completely master this technique.
In TuxGuitar you specify the pinched harmonics exactly the same way you specify an artificial one. You choose one from the harmonics list - octave P.H(12), double-octave P.H.(5), octave+fifth P.H(7), double octave+major third P.H(9) or double octave+fifth P.H(5).
Read more about pinched harmonics on Wikipedia, or see an example video on YouTube.
Tapped harmonics are very similar to artificial harmonics, but the main difference is that you don’t pluck string in any special way. You just tap the string on the place harmonic is placed, after plucking or even without any plucking.
In TuxGuitar tapped harmonics are specified exactly the same way as artificial or pinched harmonics. They even sound the same, but the playing technique should be different.
Read more about tapped harmonics on Wikipedia, or see an example video on YouTube.
Semi harmonics are in fact harmonics that are not played in the “correct” manner, so you can hear both harmonic and original note. They are most commonly used as “pinched harmonics gone bad”, and are very often used by many guitar players.
In TuxGuitar tapped harmonics are specified exactly the same way as artificial, pinched or tapped harmonics, they just don’t sound the same.