On April 16, 2024, a Te Deum must resound under the vault of Notre-Dame de Paris. On that day, the cathedral will in principle open again for worship, five years after the fire that ravaged it. “This Te Deum will have the same symbolic significance as the Magnificat interpreted in August 1944. It will mark in a festive and solemn way a liberation”, underlines Henri Chalet, choirmaster of the master’s degree at Notre-Dame de Paris.
→ DOSSIER. Fire of Notre-Dame de Paris, a year later
Liturgical singers, organists, clerics and laity, faithful and tourists, all are impatient to return to Notre-Dame and hear again singing its stones or resounding its silences. But will the acoustics so particular of this imposing building ever be the same?
An acoustician and a sound archaeologist to lead the “acoustic” group
Scientifically define the sound environment of Notre-Dame and formulate recommendations to find this lost world as best as possible, such is the mission entrusted to Brian Katz, acoustician, CNRS research director, and to Mylène Pardoen, archaeologist of the sound landscape, who lead the “acoustic” expertise group for catering.
→ MAINTENANCE. Notre-Dame, “The liturgy makes the stones resonate”
Brian Katz, who has measurements made on site in 2013, performs digital capture and acoustic simulation of the cathedral. Mylène Pardoen feeds it with history, creating an audio mix guided by the archives. But to account for a moving and intangible sensory reality comes up against a great difficulty. “Words are too poor to describe the soundscape”, she regrets.
For “Provide recontextualized sound facts in an acoustic environment”, their small team of six experts works “To reconstruct the everyday sound environments by layers of noise” relying on “Sound recordings, in order to recover the waves and thus create an acoustic volume”.
Gather information from all possible sources
” Our work, summarizes Mylène Pardoen, is like building a virtual ship that takes you back in time. We imagine the sounds of the past: in the Middle Ages, they were different because of another interior arrangement – a rood screen, tapestries… We project those of the future, for example if we added a partition of plexiglass here or there to protect a artwork. “
→ LONG FORMAT. Notre-Dame de Paris: duels at the foot of the towers
It’s about gathering information from all possible sources, “Nature, geography, wind, human noise, the sounds of the forecourt, traffic flows …”, and confront them with the sounds of the cathedral, “Masses, concerts and less dense atmospheres, not monks, or rumor of visitors”. Brian Katz models these acoustic volumes with the absorption coefficients of the different materials, integrating sound and its reverberation in this place of life, worship and tourism, prayer and music.
A poignant nostalgia
The masters of Notre-Dame, the cathedral’s singing school and choir, as well as the organists, Olivier Latry, Philippe Lefebvre and Vincent Dubois with the grand organ, Yves Castagnet with the choir organ, daily accompanist of the liturgy, acquired them also a great science of the sounds of the building. “I’m trying to tame the acoustics of this very populated place that you have to learn to master”, says Henri Chalet. In this ship, you have to find “Places that sound good for each repertoire”.
With an immense privilege of which the singers and musicians of Notre-Dame keep a poignant nostalgia, “To be alone every night to rehearse”. A unique opportunity to try different placements: facing the audience to project the sound, in front of the altar to better disperse it, scattered on the sides to give listeners the feeling of being surrounded …, each time the resonances are different.
The great organ, instrumental jewel of the cathedral
The 160 master singers adapt their vocal technique and their tone to the cathedral, “In order to radiate without forcing their voices”, serving a thousand services a year and 60 concerts. Sacred music, written for places of this magnitude, unfolds there. Henri Chalet remembers a Te Deum by the Estonian composer Arvo Pärt repeated in the modern Philharmonie de Paris before being performed in the cathedral. “The resonance of Notre-Dame made evident this slow music which plays a lot over time. The work took on its full meaning in a magical moment! “
The bells, “Brass voice singing in 300-foot stone flutes “, According to Victor Hugo; the emergency sirens of the Quai des Orfèvres or the Hôtel-Dieu; the riverboats revolving around the Ile de la Cité with a serious, very slow sound, “Sixty seconds during which the singers freeze before resuming”, says Henri Chalet; a whole symphony is played at Notre-Dame.
→ VIDEO. At Notre-Dame, in the body of the organ
The soloist is the great organ, the instrumental jewel of the cathedral. “We can thank Viollet-le-Duc and his whims, smiles the organist Olivier Latry. As he imposed his architectural choices on the organ builder Cavaillé-Coll, he gave him free rein to harmonize it. “
Exploiting the soundscapes of the past
Cavaillé-Coll has endowed his masterpiece with a wide symphonic palette and a harmonic pyramid creating a feeling of power and mystery. Its low notes, of which you only feel the vibration, bring out the purity of the treble. “The large organ allows a lot of variety in colors and harmonics, and to explore all playing families; anywhere in the cathedral you can hear him enveloping you as if he were creeping into every pore of the stone “, said Olivier Latry.
Covered with dust and lead, the instrument will be dismantled, decontaminated, each of its many delicate parameters will be checked … Three years of work! “We will have to restore the sound to a coherent whole, concludes Mylène Pardoen. Notre-Dame is still there, we must keep its uniqueness. “
According to her, in the event of reconstruction with identical materials of all that was destroyed below the vault, “Minor differences would be visible in our models but not audible to the ear. The sound found would not be so different from that which we remember ”. The “acoustic” group is working to restore it, exploring the sound environments of the past to better prepare those of tomorrow.
A sound vessel
Notre Dame de Paris measures 127 m long and 48 m wide, giving an indoor area of 4,800 m2, total of 6,000 m2. Its spire culminates at 96 m, its towers rise to 69 m, and its height under the arch is 33 m.
To listen : “Notre-Dame, Cathedral of emotions” recordings of the mastery of Notre Dame, Warner, available in streaming, in CD on May 15 (€ 1 per CD paid to the Notre Dame Foundation).