The sonification was designed for an article that compared three different approaches to the sonification of the same data-set in the IEEE Journal of Intelligent Systems [Hearst, 1997]. The scenario involved monitoring the break down of a ship turbine system over an eight minute period. The data-set consisted of a timeline of values from sensors in various parts of the system that were trending towards dangerous levels at various times and rates.
The sonification design was a further extension of the Van Noorden gallop used in previous case-studies. In this instance the gallop consisted of three reference tones interleaved with four tones that summarised turbine sub-systems. In normal operation the reference tones produce a regular beep-beep-beep figure that stands out against the lower and more variable background of the subsystem tones. As a subsystem variable moves towards a dangerous level the related tone begins to group with the reference figure and disrupts the regularity to produce a different rhythm. The 25 possible variations in the figure are not pre-ordained to signal specific states, but emerge from the relations between the variables. The reference figure becomes increasingly insistent and dominant as more subsystems group with it, until it sounds like a conventional alarm in the last minutes of the emergency.
The Dissonance and Streaming case study is significant because it develops a way to monitor continuous information about a system that is not based on pre-specified alarm triggers. An awareness of the continuous state of the system may enable the operator to predict and prevent a problem before it reaches an emergency situation. The emergent sonification is specific to the system and different examples of the same system will sound similar but different. The operator may pre-learn important general states but over time more specific meanings may emerge with experience with a particular system.
Here is a short 2 minute overview.
Some questions for further investigation coming out of this case study include: How many variables can be monitored with this figure/ground interleaving technique? How effective is this technique for the ambient awareness of a system for periods of an hour, a day, a week or a month? How many specific states or conditions can be recognized with this technique, and how long do they take to learn?
An important aspect of a complex intelligent system is the human-computer interface. Although most readers of IEEE Expert are well-acquainted with graphical user interfaces, in this installment of the Trends & Controversies department we discuss the perhaps less-familiar topic of audio interfaces. The controversy surrounds which of three competing audio interface approaches is most effective: Sonification (Stephen Barrass), Earcons (Stephen Brewster), and Auditory icons (Beth Mynatt).
To help facilitate comparison, each audio expert has described a design using their approach for an example problem, created specifically for this discussion by Michael Albers (Sun Microsystems).