4 Example #2: The Great American Eclipse
The total solar eclipse that took place on the 21st of August 2017 projected the moon's shadow diagonally across the North American continent. The population of 12.25 million people living in the path of totality, combined with live-stream video watched by many people across the world, could arguably have made this event one of the most watched in history and a truly shared social experience.
One of the unique features of the solar eclipse is that in order to view it, one has to wear special-purpose solar filters (a.k.a. “eclipse glasses”) that block almost all light. Even the darkest of sunglasses transmit thousands of times too much sunlight to be safe for viewing. These glasses create a special kind of “blindness,” where viewing the sun is only possible at the expense of viewing anything else. Figure 3 displays a person wearing eclipse glasses.
Thus, although the primary motivation for designing an eclipse sonification was to include individuals with visual impairments who might otherwise have been left out during this rare shared experience, the reduced visual capabilities experienced by all viewers made the eclipse sonification a perceptual enhancement for everyone.
To make the sonification available synchronously to large numbers of people at different locations, the eclipse sonification was hosted on a public-facing website synchronized with the unfolding time-period of the eclipse. Although different locations experience different eclipse durations, we focused our design on two cities: Hopkinsville, Kentucky (the site of maximum total solar eclipse), and Atlanta, Georgia (a site of non-total overlap). The data was transformed into sound using the Data-to-Music sonification API (Tsuchiya, Freeman and Lerner 2015), Supercollider and sample sounds from Ableton Live.
4.1 Archived Interactive Demonstration
An archived interactive demonstration of what audience members heard during the eclipse is now available on the eclipse website, and we encourage the reader to explore this site to listen to the sounds and apprehend the mappings. The online archive includes a total of 40 minutes of audio, including different “movements” of the piece and different “events.” An information button in the upper right-hand corner allows the user to read about the sounds and mappings used in more detail. Figure 4 displays two screenshots from the interface, taken 20 seconds before and 20 seconds after totality.
Figure 4: Two screenshotrs from the Live Interactive Demonstation. The background shading of the interface reflects the ambient light level, so 20 seconds before totality is much brighter than 20 seconds into totality. The corresponding sounds of these two moments bear this distinction as well.
The first section of the piece starts about 30 minutes before totality and represents the progression of the moon towards the sun. It develops slowly, rhythmically capturing the building anticipation with its increasing tempo. About 15-20 minutes before the totality, the excitement rises. The piece transitions into a new section, almost breaking down the rhythmic elements into a crushing soundscape, when suddenly the moon has covered so much of the sun that it starts to appear bigger. In this section, one hears what sounds like a duel between the sun and the moon – the harsh-sounding sun and the mellow-sounding moon. You can hear the moon slowly overcoming and soothing the soundscape. Finally, you hear a last retort from the sun, and then the piece builds up toward the dramatic totality. At totality, you hear nothing but a low lingering presence of the corona of the sun. Then, the sun reemerges into another hopeful post-ecliptic phase and fades into the day. A diagram displaying the data used for the sonification is displayed in Figure 5.
Figure 5: The figure shows a visual representation of two parameters mapped to the synthesis unit generating the ascending tone during the totality phase of the sonification. The abscissa spans the time from the start of totality, to the maximum overlap, to the end of totality. The brighter line represents the amount of the sun's visible surface mapped to the band-pass filter frequency and the darker line represents the intensity of light mapped to the amplitude modulation.