Learning Tone Master Posts: 861
Joined: 31-December 10
From: Sweden
Ok, so a while back in the Tuesday video chat, I tried to make a point by streaming video but the resolution did not allow for the required detail level. I therefore promised Darius to post a video to illustrate what I meant. I decided to also write down a few words in this context.
H
Without delving too deeply into details on properties of different materials, and avoiding technical talk about wave lengths and frequencies, there are three physical factors that are of practical importance for guitarists when it comes to affecting the pitch of a string: thickness, length, and tension.
A thick string gives a lower pitch than a thin string. A standard set of strings has the thicknesses adapted so that all strings have the same tension when the guitar is tuned in a standard fashion. Once the strings are in place, there's not much we can do to affect a string's thickness while actually playing, but we can use different string gagues for different situations.
A short string gives a higher pitch than a long string, making length our most critical factor - fretting adjusts, in discrete steps, the length of the vibrating part of the string, i.e. the distance between the two points to which the vibrating part of the string are attached namely the bridge and the fret.
A tense string gives a higher pitch than a loose string. This is widely employed among instrumentalists to add to the expression via small, continuous changes in the pitch (vibrato) and/or continuous transformations of the pitch between two discrete steps (bending).
Bending/vibrato can be applied in three dimensions, which we consider separately below, although in practice it is usually a matter of a combination of the three.
(1) Perpendicular to the fretboard. Applying too much pressure on the string at a fret (or rather between two frets) increases the tension and thus gives a wanted or unwanted increase in pitch. This is part of the explanation to why beginners sometimes sound out of pitch even if their guitar is in tune, especially when playing chords (more than one string is fretted at once), as their fingers are still getting used to applying as little pressure as possible and at the right spot in order for the string to produce a clean sound. With a scalloped fretboard this can be and has been used with great success to literally add a dimension to the vibrato. The opposite direction (up and away from the fretboard) has little or no practical use.
(2) Parallel to the frets. This is the most common type of bending/vibrato. While the string is kept fretted, pushing or pulling the string parallel to the fret does increase the length somewhat (Pythagorean theorem), but the effect of this on the pitch is invalidated by the increase in tension, giving the string a higher pitch. By pulling and releasing, we make the pitch hover at and above the original pitch.
(3) Parallel to the strings. Fretting with e.g. 3rd finger, two fingers can back up the strength needed to pull the string laterally in either direction. This is sometimes referred to as classical vibrato, since this lateral motion is the same as used on e.g. a violin which has no frets. Pulling the string towards the headstock increases the tension and thus the pitch, while pulling it towards the bridge releases the tension giving the string a lower pitch. Thus this can make the pitch hover above as well as below the original pitch.
See the video for a description of the three.
Circular vibrato uses a combination of (2) and (3).
HungryForHeaven Vibrato In Three Dimensions Nov 2 2013, 12:29 PM
