"
Honor, common sense, the superior interest of the Fatherland, command all free Frenchmen to continue the fight
".
These words, many are those who read them with, in mind, the theatrical voice of General de Gaulle slightly sizzled by the microphone of the BBC.
But these words are not taken from the Appeal of June 18.
They were recorded four days later, on June 22, 1940. Of the famous founding speech of the Resistance, delivered on the English airwaves, no recording, neither audio nor video, was made.
This is how scientists took up the challenge of reconstructing the general's voice as it should have been at that precise moment.
Thanks to new technology, and based on historical documents, direct testimonies and the official manuscript of the speech, investigators from the newspaper
Le Monde
, in partnership with the Institute for Acoustic/Music Research and Coordination (Ircam) and its technological subsidiary Ircam Amplify, broadcast on January 18 a reconstruction of the speech by the leader of Free France.
Craftsmanship
To do this, the actor François Morel lent his voice and agreed to imitate a speaker of the time.
He first recorded himself while delivering several speeches by General de Gaulle, after June 18 and recorded by the BBC.
Then, using an artificial intelligence system, the researchers combined these recordings with the sound of the general's own voice.
"
Our system has 'learned' from several speeches by De Gaulle, which are from the period, and from several recordings by François Morel (...) we obtain [thus] an imperfect voice
", explained Axel Roebel, the one of the researchers, at France inter.
The final stage is post-production, with the sound engineers here at Ircam.
There is craftsmanship behind it
”.
In order to reconstruct the original text as faithfully as possible - the published versions diverge - journalists Charles-Henry Groult and Benoît Hopquin delved into the archives of the Swiss secret services, where a German version was miraculously found.
This had been produced by a military listening service on... June 18, 1940.