Glissandi along strings
(when a corresponing key is pressed)
For glissandi executed without pressing a corresponding key, see this page.
What happens when gliding an object along a string with sufficient amount of pressure, is that the speaking length of the string becomes shorter and the pitch higher than its original.
The object must also be made of a material hard enough so that it can offer a clean termination from which the string can vibrate, without buzzes. In front of the dampers, there is usually not space for raising the pitch very much more than a whole-tone. Behind the dampers there is more space, but then a sharper object is required.
A steel string glissando generally works more effectively, because of its smooth surface, than a glissando on copper-wound strings.
It is possible to make larger glissandi behind the dampers of the middle range, and George Crumb, in for instance his “Vox Balaenae”, suggests a chisel sliding along a string course to even make melodies.
For piano safety reasons, the edge of the chisel should be slightly dulled, but a suitable object made of brass, which is softer than steel, would be even better. Guitar slides (made from glass or brass) may also be used. A double glissando is clearly heard, as pitches from the string on either side of the object are generated.
Especially on the copper-wound strings, something softer than steel is highly recommended. A short, cylindrical piece of hard wood works for bending, and one can raise the pitch more than a whole tone, by rolling it onto the string(s) with a decent amount of pressure. If using less pressure, the glissando may turn into a harmonic glissando instead.
In Boiling Web by Øyvind Mæland, there is a piece of styrofoam that is frequently tilted in order to create short, aggressive glissandi in the high range.
This technique also includes the use of a vibrato, as f.ex. when I let a ball of glass quickly roll (with pressure) back and forth along the bass strings in Keiko Harada's 唄-媒-培 (BAI-BAI-BAI).
Examples of works including this technique:
- Keiko Harada: 唄-媒-培 (BAI-BAI-BAI)
- Øyvind Mæland: Boiling Web