Geoscience Reference
In-Depth Information
5.5 Sound Pressure Level
Although END noise mapping is standardized, the color schemes used for
the presentation of sound pressure level differ extremely and particularly
lack in an appealing design (Working Group on the Assessment of
Exposure to Noise 2008). Frequently, public authorities apply contrasting
or unintuitive colors recommended by ISO standards that contradict
established cartographic practice (Brewer 1994). We suggest an encoding
that adopts functional requirements but results in an effective sequential
color scheme (
Fig. 5
). We insert perceptual steps of saturation to match the
logarithmic nature of sound pressure level. The candidate color schemes
are approved and validated by user or usability studies (Harrower and
Brewer 2003). A sequential color scheme indicates order and qualifies for
the presentation of numerical or ordinal parameters. As sound pressure
level is a logarithmized and normalized derivation from sound intensity,
the visual encodings differ concerning their variation of color saturation.
We employ sequential schemes consisting of single hues to assure the
compatibility with the visual encoding of sound sources.
