What is a Harmonic and how do you preform one?

Alvaro Martín Gómez A.;1856503 said:

When you play an open string, you only hear one pitch, but along with it, there are lots more. The pitch you can hear is called the fundamental (the lowest possible pitch within the current length of the string), and the other (called overtones) are the harmonics. The number of harmonics determines the timbre of the instrument.

Let's say that the fundamental is the first harmonic. The second one is found at half (1/2) the string, and it's an octave higher of the fundamental. Halfway the string equals fret # 12: Just one node, as those "sweet spots" are technically called.

The third harmonic can be found at 1/3 of the string length. In other words: Dividing the string in three parts gives you the points (nodes) for the 3rd harmonic, and there are two: At the 7th fret and at the 19th fret. This harmonic is the fundamental plus an octave plus a perfect fifth.

Now, here's where the situation you ask appears: The fourth harmonic (fundamental plus two octaves) can be found at 1/4 of the string length. Likewise, dividing the string in four parts gives you the nodes for the 4th harmonic, and there are three: At the 5th fret, at 12th fret and at 24th fret, but wait! We already found the second harmonic at the 12th fret! Anyway, regardless of the octave in which it's found, at frets # 5, 12 and 24 you get the same pitch. At 5 and 24 you get an octave higher than at 12, because it's already the node for the second harmonic.

And so on: You can find the 5th harmonic (fundamental plus two octaves plus a major third) by dividing the string in 5 parts, which gives you 4 nodes (frets 4, 9, 16 and "28"). With the sixth harmonic (fundamental plus two octaves plus a perfect fifth) you get again "repeated" nodes: Dividing the string in six parts, you get 5 nodes at frets 3, 7 (which is already a node for the 3rd harmonic), halfway between frets 12 and 13 (practically unaudible because of its nearness to the second harmonic, which is stronger. You can get a glimpse of it by tapping it ala Van Halen), 19 (also for the 3rd) and "31". The higher the harmonic, the higher the pitch, the higher the number of available nodes and the harder to get.

I tried to do my best to sound the less complicated possible. Please excuse me if it wasn't like that. Hope this helps.

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Alvaro Martín Gómez A.;1954967 said:

I tried to explain how natural harmonics work in this thread (and there are great explanations by other TB members also):

http://www.talkbass.com/forum/showthread.php?t=160618

You should understand that first to get confidence with pinch harmonics. Assuming you read and understood the explanations in the above thread, so pinch harmonics work like this:

Natural harmonics are based on the full length of the string (from bridge to nut). If you want to play them using your right hand alone, you can use your thumb for locating the nodes (by touching the string, not pressing it) and use your index and/or middle finger to pluck the string. Your right thumb becomes the left hand finger you use for getting the nodes, so your left hand is now free and you can use it to "trick the string": If you fret a C on the G string, 5th fret, for instance, the "harmonic nodes' relationship" is transposed by that interval, because the string length has been shortened. On open strings, the middle point (2nd harmonic) is on the 12th fret. By fretting on the 5th fret you are transposing the whole harmonics' layout by five frets. So, when you play artificial (pinch) harmonics, you right hand must follow your left hand's movements (position shifts). Playing a major scale with pinch harmonics is a good way to start getting used to the technique.

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