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  • Heat and the Heartbeat of the City:Sonifying Data Describing Climate Change
  • Andrea Polli, artist (bio)

According to a 1999 report of the Environmental Defense Fund, New York City will be dramatically impacted by global warming in the near future. Average temperatures in New York could increase by 1-4° Fahrenheit by 2030 and up to 10° by 2100. According to the Metropolitan East Coast Assessment, the impacts of these changes will be great [1].

Heat and the Heartbeat of the City (launched 1 December 2004: <>) is a web site that presents a series of sonifications illustrating projected climate changes focusing on the heart of New York City and one of the city's first locations for climate monitoring, Central Park (Fig. 3). Listeners travel forward in time at an accelerated pace and experience an intensification of heat in sound. In addition to the web site, the project has been presented as a multichannel stereo headphone and speaker installation.

To produce Heat and the Heartbeat of the City, I worked in collaboration with Cynthia Rosenzweig, David Rind and Richard Goldberg at the NASA Goddard Institute for Space Studies and Columbia University. Rosenzweig is a senior research scientist and the leader of the Climate Impacts Group. She focuses her research on the impacts of climate variability and change on systems and sectors at regional, national and global scales. The Climate Impacts Group had created one of the most detailed climate models of an urban area. They provided me with actual data from summers in the 1990s and projected data for summers in the 2020s, 2050s and 2080s formatted especially for the creation of sonifications.

As part of the development of the sonifications, a series of videotaped discussions with Rosenzweig were held and placed on the site. Through the discussions, I took note of indicators in the data connected with effects on the population. One clear indicator was that the effects are amplified when there is a buildup of hot days. For example, each consecutive hot day sees an increase in energy load and emergency room visits. In order to express these negative effects, I not only mapped the sounds to the temperature values directly, but increased the intensity of the sound when groups of consecutive hot days were found. The sonifications focused on expressing the effects of days over 90° Fahrenheit, an uncomfortable temperature. If the number of consecutive days over 90° increased, I would attempt to create an "uncomfortable" change in the sound.

I increased the intensity of the sound by increasing the pitch and loudness. In previous work with storm data, I used the data to control the filtering of source sounds with a wide frequency spectrum [2]. For this project, I filtered similar source material using temperature data. On comfortable days, filtering was increased to create cleaner sounds. As heat increased, filtering was reduced, creating more noise.

The speed at which the data was translated into sound played a significant role. The Climate Impacts Group provided one value—average daily temperature—for each day during the summers (approximately 90 days) of each of the 10-year periods. That translated into approximately 900 values for each decade. I wanted to give listeners a detailed sense of the climate

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Fig. 3.

Andrea Polli, screen-shots and screen detail of Heat and the Heartbeat of the City, a web-based interactive work featuring a video interview with Cynthia Rosenzweig, 2004.

(© Andrea Polli)

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of each decade while still creating a listenable composition, so each of the final compositions were approximately 7 minutes long, reading and translating approximately 2 temperature values per second. A smooth transition between each value was made using digital signal processing in Max/MSP. Although the sonifications focused on temperature, the sonification of an additional variable, precipitation, was added to provide more variety to the compositions.

The sonifications were created in Max/MSP using the custom object Datareader. I developed Datareader with the help of programmer and video artist Kurt Ralske <>. The Datareader software and its source code are available at <>.

The final sonifications were placed...


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