Thursday, March 10, 2016

What Harmonics Do You Get from Strings' Physics?

By dividing the string in specific ways, harmonics are produced. Stringed instruments are capable of producing an eerie effect called harmonics. These harmonics are present in every instrument, but because of the nature of sound production, they are only audible with a stringed instrument and piano. It is possible to independently isolate harmonics on strings in a multitude of ways. The string player needs to be aware of the harmonics that are available and how to produce them.

Overview

Stringed instruments typically produce their sound through the use of a bow pulled across the string or by plucking the individual strings. To produce sound with a bow, the instrumentalist will press a string against the fingerboard by use of a single finger and then pull the bow across. Plucking the strings does not require the use of the bow and the instrumentalist simply plucks the string. Harmonics require a different technique, as the process involves splitting a frequency in half.

Natural Harmonics

Natural harmonic production occurs by lightly touching a string at different points along the string called nodes. This differs from the traditional method of playing since the string and fingerboard do not touch. By touching the string in the middle, you are effectively doubling the vibration and creating a frequency that has a ratio of 2:1 on a regular string. This doubling of the frequency will produce a pitch that is exactly one octave higher than the natural string.

Partials

Partials refer to a concept in physics called the overtone series. The overtone series produces a fundamental tone that the ear perceives and then several imperceptible tones above that initial tone. The imperceptible tones become audible on a stringed instrument by lightly touching nodes. Several partials emit different tones from the series. The first partial uses an open string and produces the fundamental pitch. The second partial requires that the string be touched midway between the bridge and nut. This doubles the frequency and emits a pitch an octave higher.

Artificial Harmonics

Artificial harmonics produce harmonics using a different method. The performer has to press down on the string to create the desired pitch and lightly touch a node a fourth above the pressed note. When pressing a note against the fingerboard it effectively shortens the string; because of this, these harmonics are artificial. The normal method of producing artificial harmonics compounds the frequency of the string and causes it to produce a sound two octaves higher.