The fire that ravaged Notre-Dame on April 15, 2019 seems to have miraculously spared the Grand Organ of the cathedral. CNRS research director at the Jean le Rond ∂'Alembert Institute1 and head of the Lutheries - Acoustique - Musique team, Christophe d'Alessandro is also the organist of the Sainte-Élisabeth organ in Paris. It is part of the National Commission of Architecture and Heritage, which will be consulted for the restoration of the Notre Dame instrument steeped in history.
A colossal site
Two organs previously resonated throughout the vaulted ceiling of Notre-Dame: the grand organ was designated a historic artifact and the more modest choir organ, located at the crossroads of the transept near the place where the spire collapsed in the fire.
"Following the first verifications, it seems that the choir organ has been damaged by water rather than by fire, but the great organ has been largely spared. Protected by a slab of stone, it has not been flooded, the pipes have not melted, the console is intact, except of course a large amount of dust, "says Christophe d'Alessandro.
Even if we still have to wait for further expert assessment, the researcher says that there should be "nothing irretrievably lost, a priori". However, dust, soot and intense heat from the fire may have affected the instrument.
According to Christophe d'Alessandro, "the organ cannot be truly restored until the building is ready," because the masonry work that will be done in the building could damage it.
"The plan is to box up the organ to protect it during the reconstruction of the cathedral, which is less dangerous than dismantling and removing it. It will also need the dust removed, as well as retuning, which requires each of the 7374 pipes to be adjusted to the nearest hundredth of a millimeter. The organ will need extensive work done over several months, or even several years if the damage proves to be more substantial, because there is no electricity for the moment and it is therefore impossible to check the instrument’s functioning", specifies says the researcher.
A monumental instrument
As wide as the nave of the cathedral and about twenty meters high, the grand organ of Notre-Dame de Paris is one of the largest in France. Exceptionally large, it is composed of many elements including a forest of 7374 pipes of wood.
The organ’s console is a veritable cockpit for the organist and includes the five hand keyboards, the pedal keyboard and a hundred or so tie rods that make it possible to call different sets of pipes.
"Every time you pull a tie rod, you activate a row of pipes,” explains the researcher. “Each row of pipes has a different tone quality that sometimes bears the name of an orchestral instrument (such as oboe, flute, trumpet or cello) and that can be mixed or dialogue with other pipe sets."
A Witness to History
Placed under the sunset rosette, this monumental organ benefits from the extraordinary acoustics of the building, which serves as a sound box. The sound can reverberate for 8 seconds. It is the voice of the cathedral. From the marriage of Henry IV to Napoleon's coronation and the liberation of Paris in 1944, the organ for the tribune accompanied the grand dame in the historic moments of France.
"Present during all the important events of Notre-Dame, the grand organ, like the bells, represents its sound identity. We came from all over the world to hear this organ, and the greatest organists played it, "says Christophe d'Alessandro.
Previous restorations trace the history that has shaped it. Built in the early 15th century on the stone platform above the large west gate, the organ has evolved over the centuries.
"The organ is a palimpsest2 ," says the researcher. “Meaning that the instrument has different time periods that overlap. The buffet, which is the visible part of the console and pipes, dates from the eighteenth century, while the pipes are seventeenth, eighteenth, nineteenth, twentieth and even twenty-first. Successive restorations have always aimed at modernizing the instrument by adding new pipe sets, computerizing transmissions, and improving the ergonomics of the console."
The last renovation of the organ was in 2012. It lasted two years during which the instrument was completely dismantled, the computer transmissions changed, the old mechanisms renovated, the pipes of facade restored and the console was entirely replaced.
In order to restore the sound of the grand organ to its full capacity before the tragedy, the experts will be able to rely on the work of the Lutheries - Acoustics - Music team. This group from the Jean le Rond ∂'Alembert Institute and member of the Collegium Musicæ at Sorbonne University is working on the reconstruction of acoustic spaces lost or transformed using virtual reality and computer simulations. In 1987 and 2015, the team had already carried out two acoustic measurement studies of the cathedral. With these measurements, Brian Katz, a 3D audio specialist, created a digital model of the acoustics of Notre-Dame de Paris, which will be able to serve as a sound comparison for the restoration of Notre-Dame de Paris and its grand organ.
1 Co-supervised by Sorbonne University, CNRS,and the Ministry of Culture
2 A palimpsest is a manuscript made up of a parchment already used, the inscriptions of which have been removed so that it can be written on again.