Figure 1: A figure displaying a stunning visual display in Fernbank's 70-foot diameter hemispheric SciDome.
During the “Planetary View,” the audience journeyed to the individual planets and listened to an auditory rendering of their unique characteristics. This included the presence of any moons or rings, temperature range, and gravitational pull. As displayed in Sound Samples 8-11, the number of moons was conveyed by a corresponding number of short sinusoids with random frequency randomly distributed around the hall. As displayed in Sound Examples 12 and 13, the number of rings were conveyed with a corresponding number of randomly distributed frequencies slowly fluctuating in volume. As displayed in Sound Examples 14–17, the temperature range of each planet was conveyed as a sequence of notes that ascended or descended in pitch, with lower pitches indicating the lower temperatures and higher pitches indicating higher temperatures. Finally, as displayed in Sound Examples 18 and 19, gravitational pull was conveyed by dropping a virtual ball from a small height onto a virtual surface of the planet. The sonified trajectory of the ball (i.e., the decay of its bounces) indicated the strength of the gravitational pull.
3 Example #1: Solar System Sonification
Our first example is the “Solar System Sonification” planetarium show that debuted at the Fernbank Science Center Planetarium in April 2016. The planetarium featured a 70-foot diameter hemispheric SciDome for video projection, originally dedicated to “teaching and public enrichment.” While many planetarium shows attracted audience members to stunning and immersive visual spectacles, ours capitalized on the planetarium's quadraphonic speaker system and advertised a listening experience mediated by sonification. Figure 1 displays a captivating visual from the projection system. A poster presenting an advertisement for the planetarium show is presented in Figure 2.
Figure 2: A poster advertisement for the show. It reads Solar System Sonification: Exploring Earth and Its Neighbors through Sound.
The 40-minute show included multiple sections that highlighted specific learning concepts, organized into two sections or “views.” In the “Solar View,” planets rotated around the audience, simultaneously conveying their mass, year length, and day length. Sound Example 1 plays the masses of all eight planets in their customary order, demonstrating that low mass planets were high in pitch, and high mass planets were low in pitch. Sound Examples 2 and 3 display the day length for the four inner and, subsequently, the four outer planets using the frequency of a full-range amplitude modulator. Sound Example 4 displays the relative year length for the first four planets with a stereo mixdown of the original quadraphonic sound design. The solar view ended by taking a trip from the sun to planets in an “auditory spacecraft.” Sound Example 5 displays an excerpt of the spacecraft, which would play for the duration of travel between planets as if the spaceship were travelling at 0.2 AU per second. Because the outer planets were much further away, the playback rate of the loop was sped up by a factor of 5 (1AU/sec, Sound Sample 6) to reach Jupiter and Saturn and then by a factor of 10 (2AU/sec, Sound Sample 7) to reach Uranus and Neptune.
Beyond the sonification, two narrators engaged in dialogue to provide context and a mapping introduction for each auditory scene. They would introduce every new scene or view and, where needed, explain how the sound represented the data. They would provide additional context cues, such as saying the planet’s name. To assist in establishing conceptual anchors for the sounds, publicly available photographs of each planet were used as basic visual anchors for the audience.
After each of the two sections, we conducted an open-ended user experience evaluation: a series of Likert questions adapted from Matthews (2006) work on peripheral display interpretation to measure the helpfulness, appeal, and learnability of the mappings used in both halves of the sonification. The audience rated each of the sonifications quite positively, with a mean score of 4.7/6 for the mappings in the first half and 4.6/6 for the mappings in the second half. Tomlinson et al. (2017), mentioned above, describes the evaluation results in more detail.
The audience found this experience enjoyable, and many provided feedback through open-ended responses on what mappings they found most interesting, intuitive, or striking. Some found that the sonification evoked unexpected positive feelings, including feelings of how “awesome” the size and scale of the solar system really is. Attendees reported having more trouble remembering the sonification mappings from the second half. This view displayed more details specific to each planet and presented many more pairs of data comparisons than the first half. Breaking this section into smaller chunks would make it easier for the audience to enjoy and reflect on the sonification.