sound program
The sound of the project will consist of 35 audio channels across the façade of Building 54 (see detail). The speakers will represent the temporal change of conditions in the plasma which composes the ionosphere, a layer of the upper atmosphere that starts at an altitude of approximately 100 kilometers (60 miles) above ground. For the purposes of this project, the thickness of the ionosphere is subdivided into 7 layers. Each of the 7 horizontal speaker rows will sonically reflect the current composition and temperature of electrons and ions at a specific altitude, analogous to the elevation of the rows from the ground on the Green building. The vertical extent of the Green building façade becomes a representation of the ionosphere layer.
The sound that will be broadcast from the speakers is based on a translation of ion pressure waves within the ionospheric gas, transposed into audible frequency range. These pressure waves have a characteristic frequency spread which depends on the composition and temperature of the ionospheric gas itself.
The sound will vary from left to right to represent different discrete frequency bands from within the frequency spectrum of the sound translation. The bands will increase in frequency range from the left to the right. The distribution of speakers on the façade reflects the frequency distribution of the sound generated from the ionosphere pressure waves and the subdivision into different altitudes: Higher altitudes contain a characteristically wider ion-acoustic spectrum since masses are lighter and temperatures hotter there, while lower altitudes are narrower spectra typical of heavier ions and lower temperatures.
The conditions within the ionosphere undergo temporal change that will affect the sonic representations at all altitudes. The temporal variations of electron and ionic density in the ionosphere layer have complex physical responses which at lower altitudes have nearly tidal patterns, as the charged and neutral portions of the atmosphere interact with each other. Major influences on the make-up of the ionosphere are large variations both in solar radiation and in particle emission of the sun’s outer atmosphere, resulting from magnetic variations within the gaseous body of the sun. Solar winds, the term for this solar atmosphere outflow which buffets the planets, create waves of highly energetic particles which can greatly affect the ionosphere. A visible example of this interaction between sun, upper atmosphere, and the magnetic field of the earth are aurora borealis, large glowing displays that can be seen in the sky usually above the northern and southern poles of earth and even sometimes over North America (for more information of ionospheric conditions and the interaction between sun and earth, see www.spaceweather.com). Relevant to this project, in an expanded sense of meaning, the sound structures emitted by the speakers on the façade will make audible the interactions between the sun and the earth in terms of ionospheric particle and radiation influence caused by solar radiation and solar winds - in a broader sense the audible channels broadcast by the speaker field sonify the effects of solar winds on earth. The sounds are specifically representative of ion-acoustic spectra in the ionospheric gas, scaled in frequency, with physical parameters appropriate to the altitude in question.
The data behind the calculation of the audible sound, done by collaborating scientist Dr. Philip Erickson at the Millstone Hill Observatory which is a part of MIT’s Haystack Observatory, Westford, MA, stems from a large database of ionospheric studies conducted at Haystack Observatory over the past five decades using the powerful ground-based technique of incoherent scatter radar. An empirical model constructed from this data by Dr. Shunrong Zhang, also at MIT Haystack, allows for the calculation of a typical average ionospheric state (relative amounts and temperatures of electrons and ions in a given volume of ionospheric gas at different altitudes) for exactly the time frame the sounds are on display. In a statistical sense, what is audible is a representation of the physics taking place at this moment, approximately 100 to 600 kilometers above the Green building on the MIT campus.
MIT Haystack Observatory is one of four installations funded by the Upper Atmospheric Facilities division of the National Science Foundation to conduct ionospheric studies using powerful radars, and the Atmospheric Sciences Group at MIT Haystack is the only observatory in the Continental United States dedicated to this research technique. Ionospheric research is becoming increasingly important to our technology-dependent society, as changes in the makeup of the ionosphere affect the precision of GPS technology and under severe conditions can disrupt radio transmissions or any type of broadcast relayed by satellite. Knowing and predicting the composition of the ionosphere (an effort known as Space Weather forecasting) has become an integral interest for the military and commercial sector, and plays a key role in the reliability of fundamental communication requirements.
Ionospheric studies have been conducted since the beginning of the space era by dedicated groups and have recently been the focus of intense public outreach and growing public interest in both the natural and human consequences of Space Weather events. By connecting ionospheric research with this large scale sound installation, we hope to build bridges between state of the art research and contemporary art at MIT that are audible and visible to the art interested community that MIT attracts.
sound detail
