Pinch Harmonics

Pinch harmonics are high pitch squealing sounds sometimes referred to as squealies. They happen when you stop the string vibrating at a certain point along the string with the thumb of your picking hand, causing the harmonic which is when the string vibrates like this:

 The red dots are nodes, which means the string does not vibrate at that point. There can be any number of nodes and they are evenly spaced along the string. The vibration shown is the 4th harmonic. The 1st harmonic is when the string vibrates normally but guitarists do not refer to that as a harmonic. We cause the string to vibrate harmonically by stopping it vibrating at a point on the string with our thumb at the moment we pick the string. This causes a node, and for the string to vibrate the other nodes come about themselves.

We do not really need to worry about all that to perform the technique, if you do a pinch harmonic anywhere you pretty much always find a harmonic. If you divide the string in half with the pinch you create the 2nd harmonic, into thirds you create the 3rd harmonic, into quarters you create the 4th harmonic and so on. There are an infinite number of these fractions so you always make some harmonic.

To perform the technique, hold the pick between your thumb and forefinger with just a tiny bit of the pick poking out. Pick the string downwards and dig in a little, and push in with your thumb simultaneously. This should produce the squealie, but it does take a bit of practice. If you can't seem to manage try changing the position along the string, lower harmonics are easier, so the easiest to do would be halfway along the string, on the 12th fret, but the fretboard gets in the way. The easiest practical one to do is probably the 5th harmonic, this should be roughly on the bridge edge of your neck pickup if it is a humbucker, or about a 5th the way along the string from the bridge. Just keep searching around and practicing the technique and you will get it.