Page 32 - Jul2009

WHAT IS THE SOUND OF THE EIFFEL TOWER?
China Blue
256 Maple Street Warwick, Rhode Island 02888
“Social impact operating in conjunction with the structural acoustic elements creates a complex and dynamic sonic ecology that helps to extend our knowledge of how we perceive our sonic world.”
How the intersection of audio technology, architecture and art can change our perception of what we thought we knew
The sound of human spaces is
defined by human expectations.
Architects consider sound based
on how vibrations affect the structural
integrity and the acoustics of residential
and performing spaces. Bioacousticians
examine sound based on its effects on
living organisms and how it affects their
behavior in the environment. Musicians
and artists judge it by how it impacts
their creations and their listeners.
However, as in many fields, crossing cat-
egories can generate a hybridized result, and allow new, enriched sonic experiences to emerge. In the pursuit of a new way to consider the intersection between structure, space and human sound, in September 2007, I went to Paris to reexam- ine the Eiffel Tower.
My plan was to create a sound environment based on what I expected to hear—the sounds of traffic around the base, human voices and footsteps—the normal sounds we hear from any human urban space, the differences largely based on the linguistic mix of a tourist site in a foreign coun- try. But shortly before receiving authorization by the Societe d’Exploitation de la Tour Eiffel to do the recording, by chance I had come upon some near-infrasonic sound recordings based on seismic events—earthquakes, temblors, underwater recordings of tsunamis—and I was intrigued with the possi- bility of trying to expand my recordings to including what I previously had thought of as beyond human hearing—infra- sonic recordings. I managed to obtain some “can” geophones from a surplus house and after some test trials, decided to include the infrasonic and near-infrasonic in my recordings of the tower. I realized that I had no idea of what I would cap- ture (possibly nothing useful). But, following in the path of Gustave Eiffel, the builder of the Eiffel Tower who used it as his private laboratory for his scientific research, it was an experiment.
My goal was to record using two different methods. One would be to use the geophones to record the actual vibrations of the iron of the structure, the other was to record the social experience of being there. People usually specialize and record either the subsonic or the ambient soundscape, but normally not both. Yet, from my prior recording work I con- cluded that to capture the full acoustic environment, it was important to sample both ranges of the structure. By doing this I would collect not only the physical impact of the struc- ture but also the social impact. For this work I had the help of 8 technicians, 6 from France and 2 from the United States.
Seth Horowitz, a member of the Acoustical Society of America’s Technical Committee on Animal Bioacoustics, came on board as the Chief Technical Officer for the project.
The process
The multiple levels of the Eiffel Tower were the inspiration to try out multi-level recording—examining vari- ous points in the tower using multiple recording techniques. To achieve this, we used two types of microphones. The first was the can-type geophones (with resonant frequencies of ~14 Hz) con- nected to 100 meter cables. These sen-
sors are normally used for monitoring seismic activity, but we adapted them for this purpose because they would success- fully capture the subsonic vibrations. We recorded from two geophones simultaneously on separate channels onto a single 4-channel digital recorder (Zoom H4) to allow us a hard- wired method to avoid any differences in time of the arrival of sounds across the potential span of 200 meters. The next method we used was recording via in-ear stereo binaural microphones. These microphones pick up sounds that have a very human feel based on their position in the ear canal and allow the external ears to shape the sounds to be similar to what a person normally hears and create a very personalized and “human” sounding recording. The binaural recordings were captured on a Sony portable DAT deck. In addition, a third “wandering” team member carried an additional Zoom recorder using built-in microphones configured for long dis- tance (shotgun-style) recording to capture any additional ambient or transient sounds. All recordings were done at 48.1 kHz/16 bit sampling.
The planning and transporting of the equipment was an extensive and stressful process. We were traveling from the US to Paris, France with two Zoom H-4s, one Sony Digital Audio Tape (DAT) recorder, six 100 meter lengths of XLR cables, 6 customized geophones, a pile of Secure Digital (SD) memory cards and DAT tapes, and of course the inevitable rolls of electrical and duct tape. I was primarily concerned whether the equipment would pass security inspection since there was a likelihood that the equipment might look like material to create a bomb. So to avoid any problems, I placed instruction manuals for everything in the suitcase and the authorization to record the Eiffel Tower in hopes that if any- one opened the case, they would have complete description of what was inside. Fortunately we had no trouble with authorities until we were actually on site.
We arrived at the Eiffel Tower that fall morning at 9:00 a.m. with all of the equipment ready to do a test recording
Sounds of the Eiffel Tower 31