Geoscience Reference
In-Depth Information
5.1 Geometric Shape of Sound
The encoding of the geometric shape of sound employs basic graphic
elements, i.e., points, lines, and areas and matches the type of its spatial
dimensionality (
Fig. 1
). We achieve further variations by applying the
variable shape to the graphics (Bertin 1974, Wright 1944). Punctual
presentations are useful to present locally discrete phenomena, e.g., sound
particles. The usage of line segments is suitable to delimit areal
phenomena, such as contour lines of noise pollution or when sound is
modeled as rays. Additionally, spatially extended sources, such as streets
are assumed as line segments. Areal presentations indicate the geometric
shape of sound as a spatial continuous phenomenon and are commonly
used in noise mapping (MacEachren 1995).
Figure 1:
Basic graphic elements varied in shape
5.2 Sound Source
The parameter sound source is presented by the graphic variable color hue
as it is useable for nominal parameters (Bertin 1974). By this means, we
match the perceptual variation in the referent with the perceptual variation
in the phenomenon and allow for qualitative description or comparison of
sound sources. With a two-level hierarchy of sound sources we require
both an encoding of source categories with equidistant color hues and an
encoding of source subcategories with color hues that cluster around the
associated category's color hue. We use the CIELuv color model where
distances between colors are proportional to perceptual discrimination
(Wood et al. 2010, Wijffelaars et al. 2008). Additionally, all color hues
consist of 100 % saturation to allow a further encoding of this variable.
Based on a qualitative analysis of audio recordings, we come up with an
exemplary categorization of sources (
Fig. 2
). We transfer auditory stimuli
into visual metaphors by associating a source with a color hue and display
traffic with blue, economy with yellow, human activity with red, and
