Geography Reference
In-Depth Information
information which has to be processed by each perception channel. Along with this,
negative recognition phenomena might be reduced; for example the split attention
effect (i.e. the limited ability to discriminate between objects that are spatially or
graphically apart from each other; Harrower
2007
), the change blindness
(i.e. missing changes in image sequences that are too fast; Simons and Ambinder
2005
), or the visual clutter (i.e. the graphical overload; Brewster et al.
1994
). The
latter aspect is critical in multivariate maps where, for example, two graphical
variables have already been introduced for the first two topics and more themes
have still to be covered. In particular, the usage of graphics within tiny areas
becomes difficult due to space limitations, consequently leading to cognition
problems. With that, acoustic coding can be seen as an application dependent,
complementary option in a multimodal map. Finally, sound maps have still to be
considered and further developed for the 300 million visually impaired and blind
people worldwide. In this context, the availability and functionality of modern
mobile devices leads to several advantages of multimodal maps in comparison to
conventional haptic maps (Jacobson
2007
; Delogu et al.
2010
; Koch
2012
).
Based on this background,
goal of this contribution
is to investigate acoustic
options for depicting
quantitative data
and to derive recommendations for practical
usage depending on given data and purpose. In particular, representations for a
single point in time
(second section) and for
time series
(third section) will be
considered
.
This detailed and systematic analytic review goes beyond the current literature,
in particular the work done by Krygier (
1994
) who assembled the sound variables
(location, loudness, pitch, register, timbre, duration, rate of change, order, attack/
decay) in order to describe the transformation of spatial data properties into abstract
acoustic (i.e. neither verbal nor musical) properties (
sonification
). Our investigation
will consider mainly physiological and cognitive, but also practical map imple-
mentation factors.
Based on this analytical review we will briefly describe an own empirical study
as well as demands for future tests (fourth section).
Acoustic Coding of Quantitative Data for Single Point
of Time
Goal of the following analytical review is the identification of suitable abstract
sound variables for representing quantitative information for a single point of time.
This review is based on the above mentioned list of sound variables by Krygier
(
1994
). Whereas Krygier evaluated the suitability for data at nominal and ordinal
scales, an explicit systematic check for data at cardinal scale has not been
performed so far. For this the following suitability criteria are taken into account:
• There should be an analogy between metric scale and sound variable; in partic-
ular, not only a sequence of values (from low to large values) but also—in
