A Great Research Experiment

"Cornell is known not to be afraid to engage in research experiments," says Anette Schwartz, chair of German Studies, "and this organ is a great success. This experiment has worked." "It was initiated by our wonderful organist Annette Richards," adds Schwartz. "But it's not just Annette Richards alone, it's the university that supports these international research collaborations. Not every university in the States will do that." "The organ will be a historic monument at Cornell University, in Ithaca, New York. People from all over the world will come here. So I'm very happy that our university is interested in these very large international collaborations. It's great. I am a foreigner in a foreign country and I love to be in a university that's interested in maintaining and supporting research contacts with Europe and Asia."  

History Comes Alive

Detail of hand built keyboard

"When I first heard Cornell's new baroque organ played, I got goose bumps because history really does come alive in this extraordinary project," writes Leslie A. Adelson, Professor of German Studies and Director of the Institute for German Cultural Studies at Cornell's College of Arts and Sciences. "For the study of German culture it offers a treasure trove of insights into the science and technology of artisanal craft, the history and phenomenology of a nation's musical taste, the importance of German feet and pedals for sound cultures in Europe, the emergence of middle-class public culture, urban losses in modern warfare, and even the global value of sustainable forest in a country where live oak has symbolic value too. What Cornell now offers as an inspiring and moving musical experience also opens a rather large window onto early modern and modern German cultures."

Measuring the Organ

Nervous Breathing and Sensitive Pipes

Carl Johan Bergsten, a research engineer with the Gothenburg Organ Art Center (GOArt) at the University of Göteborg, Sweden, spent the 2011 Thanksgiving holiday studying the wind system and acoustics of Cornell's baroque organ. The measurements are part of a larger GOArt study exploring the interactions between bellows, wind chest, and pedals to determine an organ's sound. The dynamic behavior of an organ's wind system is complicated. Stepping on the pedals opens valves that create high and low pressure waves in the air that travels through the system. It's necessary to have some reaction in the wind system, though, otherwise the sound is too stiff, explained Bergsten. "You want to hear that the organ is breathing, but if it's too much it starts to sound nervous and it can be destructive to the organ sound. It's a delicate balance." Bergsten is also measuring how sensitive the pipes are to wind. The better the pipe, the more stable it is to the wind connection, said Bergsten, pointing out that pipes like those used in Cornell's baroque organ are more stable than ones made by modern methods. To measure the pressure and the dynamic behavior of the wind system, Bergsten installed four sensors, one each on the Rückpositiv, the Hauptwerk, the Pedal, and the bellows room. He also measured sound from near the pipes and from the floor of the chapel. The sensor system is new; previously, he was only able to measure one pressure at a time. Bergsten estimated he gathered about 15 gigabytes of data to analyze. "I'm looking for patterns or tendencies," he said. "We might find something unusual, but we're interested in overall tendencies as well." Bergsten plans to return in March and repeat the measurements, to see if there is any difference.

The Good, The Bad, and The Fingerprinted

Traditionally, organs have only been documented through mechanical measurements such as size and overall wind pressure. But this static data can't communicate the dynamic behavior of the wind system and how an organ actually sounds. So Carl Johan Bergsten, a research engineer with the Gothenburg Organ Art Center (GOArt) at the University of Göteborg, Sweden, is working on a new method that would create a "fingerprint" of the wind system, making it possible to compare different instruments and the same instrument after alterations in an objective way. He spent the Thanksgiving holiday documenting Cornell's baroque organ. Bergsten is working with a graduate student from the Chalmers University of Technology to measure key action as well the wind system. "We perform a lot of measurements, changing one thing at a time like how fast the key is pressed and released, and see how it affects things," said Bergsten. "The measurements show the kinds of decisions an artist is making." Organ designer Munetaka Yokota pointed out that "how an organist releases the chord makes a huge difference in the oscillation, because you're not closing all the pallets at the same time. The pressure waves amplify or cancel out. So these measurements could be very useful for an organ teacher in teaching how to play an old organ. You can actually see how to play." Once Bergsten has documented what sounds the organ makes, the next step is to try to define what should be considered good or bad. "We have to connect to what's really going on, what varies and if we like it--the psychological acoustics," explained Bergsten.

A Corrosive Enemy

Treating the wood that holds the pipes to combat moisture

Historic and modern organs share a common enemy: corrosion. In a surprise turnaround, scientists have discovered that the primary source of pipe corrosion is not industrial pollution, as was long thought, but the organs themselves. Or more precisely, the acid contained in organ wood. As Catherine Oertel, assistant professor of chemistry at Oberlin College, explains, wood acid causes pipe corrosion in two ways. First, by direct contact of pipe metal with wood, which is why the pipe racks for Cornell's organ pipes were charred before the pipes were inserted, neutralizing the acid transfer. But wood also excretes acid into the air in what Oertel calls "a vapor mediated process." The acid thus gets into the bellows area and the wind channels where the air collects before moving into the pipes. Oertel studied the problem of pipe corrosion as a post-doc at Cornell, collaborating with corrosion chemists at the Chalmers University of Technology in Sweden. She used high-power microscopes in Cornell's nanofabrication facilities to study how different compositions of metal alloys affect corrosion rates. She found that even a small amount of added tin can reduce the susceptibility of pipes to corrosion, and that this protective effect is extremely sensitive to humidity. Cutting-edge technology may prove corrosion's undoing: Oertel says scientists are experimenting with nanoparticle coatings that have a basic pH, which could neutralize the acid as it's emitted, eliminating corrosion invisibly.

Has Someone Been Shooting at Europe's Organs?

No, those aren't bullet holes, though the round black dots found on some tin organ pipes look like Al Capone's been using them for target practice. The holes are signs of a far greater danger to organs than a gangster's gun: corrosion. The problem of corrosion in organ pipes is not new, explained GoArt engineer Carl Johan Bergsten on a recent inspection of Cornell's baroque organ. In the 15th century an organ's pipes might have been destroyed in just 50 years. Since organ builders had no idea why, their solution was to replace the pipes. But as Bergsten said in a Newsweek interview, "These pipes are like the Stradivarius violins. No one knows how the organ builders back then made them sound so beautiful," so preserving them is vital. Thanks to the COLLAPSE research project led by Bergsten, pipe lead corrosion is now known to be caused by organic acids released from an organ's wood. These acids are airborne, and become concentrated in the pipes as they pass through the wind system. High humidity quickens the corrosive process. A new type of glue developed before 1960, PVA or white glue, also releases acetic acid. So for Cornell's organ, organic hide glue was used for the bellows and parts of the wind chest. (This glue also has the added benefit that it's easy to remove despite its strength, a plus because the leather in the bellows needs to be replaced every 3-5 decades.) Cornell's organ pipes will be examined periodically, but they have less chance of corrosion because of the low temperature maintained in the chapel- although warm and humid summer weather could prove a problem, which is why plans call for a chapel air conditioning system.

Here Shefford Baker, Associate Professor of Materials Science and Engineering, discusses research into pipe corrosion 

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