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mapping” type principle, either on the basis of elements constituting the auditory
icons or based on elements attached to auditory icons, designed via means of
external sound synthesis motor (see the following paragraphs and section 8.4.2.1);
the design parameters of earcons then being connected, in both cases, to the
navigation data like spatial coordinates (x, y): vertical depth and horizontal
scrolling.
Figure 8.9.
Process of mapping data with sound control parameters
More specifically, the parameters used in one case (case 1) are mainly the
duration and pitch, and in the other case (case 2) the tone attributes directly
controlled by the definition of the synthesis model (see Figure 8.9).
The second case (case 2) can thus resemble a “model-based” type approach.
Indeed, the earcon is produced here thanks to a physical modeling synthesis engine
that simulates a mechanical (or acoustic) system that produces a sound (e.g. a plaque
hit by a mallet or a string bowed by a bow). This system is defined via parameters
that directly influence the physical phenomenon which generates the sound. For
example, a physical model of a plate that is hit will be defined by its dimensions
(width, length and thickness) or the characteristics of the material (density,
elasticity, etc.). It is to these parameters of the model that the sonification data are
then linked together, thus enabling variation of the system - and therefore implicitly
its associated tone - according to the navigation position.
Here, also, there are potentially several obstacles that can be removed thanks in
particular to knowledge and know-how in terms of sound technologies and signal
processing:
