Graphics Reference
In-Depth Information
Sounds as Electromagnetic Waves
kinds of media: performances, live action, interac-
tive installations, visual music, and movies into
their events.
We are immersed in a variety of sounds coming
from our surroundings, music and various types of
communications. Electromagnetic waves, seen as
energy and matter that conducts the waves, oscil-
late. That means all parts of the system display
sinusoidal motion with a given frequency and an
uninterrupted pattern. Modal phenomena display
a pattern of sinusoidal motion of a physical object
(having the form of a sine wave of smooth, repeti-
tive oscillations). We call a normal mode such
pattern of vibrations when all parts of the system
(for example, molecules, drums, pipes, bridges,
or houses) vibrate with the same frequency on the
whole surface and have a fixed phase relation. Such
objects display their sets of normal modes that
depend on material, structure, and surroundings
of the object. A frequency of a normal mode of
vibrating object is called its natural or resonant
frequency. When more frequencies are involved,
an object oscillates at resonant frequencies with
greater amplitude, the maximum extent of oscil-
lations. Sound waves cause that the ear structures
pass and translate vibrations into neural messages
sent through the auditory nerve from about 25,000
receptors to the brain. The ears contain also semi
circular structures that provide the feeling of bal-
ance. Musical sound is produced by continuous,
regular vibrations, while noise is not regular.
Music, speech, and sound effects go together in
a sound studio for a broadcast production, film,
or video. Artists translate musical compositions
into visual imagery and thus create visual music.
For example, many artists presented their works
at festivals, as it happened at the N. Y. Digital
Salons, the 2009 Visual Music Marathon at the
Northeastern University, and also published their
pictures and still frames in journals such as the
Leonardo, Journal of the International Society for
the Arts, Sciences and Technology. A growing
number of competitions (such as Eurographics
- European Association for Computer Graphics,
Imagina, or Ars Electronica) incorporate varied
Cymatics
Cymatics is a study of vibration of matter that
makes sound visible. When we cover a surface of
a plate or a membrane - a thin, pliable sheet of
material with a thin layer of particles or liquid and
then produce a musical sound using for example,
strings, drums, or air pipes, the surface will vibrate
according to the music and we will see vibrations
as patterns, thus making visible what the sound
waves generate.
There is a long history of the study about
patterns produced by vibrating systems. Galileo
Galilei described the regular pattern of oscillating
object in his work “Dialogue Concerning the Two
Chief World Systems”
As I was scraping a brass plate with a sharp iron
chisel in order to remove some spots from it and
was running the chisel rather rapidly over it, I
once or twice, during many strokes, heard the
plate emit a rather strong and clear whistling
sound: on looking at the plate more carefully, I
noticed a long row of fine streaks parallel and
equidistant from one another. Scraping with the
chisel over and over again, I noticed that it was
only when the plate emitted this hissing noise that
any marks were left upon it; when the scraping
was not accompanied by this sibilant note there
was not the least trace of such marks. (1632, after
McLaughlin, 1998)
Robert Hooke examined in 1680 the nodal pat-
terns he obtained by running a violin bow across
a glass plate covered with flour. Ernst Chladni
described in 1787 such experiment, this time plac-
ing sand on metal plates and stroking the edge of
the plate with a bow, in his topic “Entdeckungen
über die Theorie des Klanges” (“Discoveries in
the Theory of Sound”). One can easily form and
