Intro
A song-podcast follows a simple principle: dedicating one podcast to a single recording from the 1932 Cairo congress. Contemporary artists, researchers and experts choose a recording and explain the reasons for their choice, followed by the original piece in its entirety.
Luc Verrier, a sound engineer at the National Library of France, played along by choosing an excerpt from a Moroccan Nuba entitledJul tara al ma’ani (“Travel the world, you will grasp its secrets”). It was performed in Cairo by the ensemble of Omar Jaidi, from Fes (Morocco).
To “visualize” his approach and hear the differences, I suggested to Luc Verrier that he introduce us to the three sound versions of this Moroccan recording: the original 78 rpm, the straight version digitised, and his final version after his sound treatment.
However, to illustrate his point, Luc Verrier also draws on other recordings from the Cairo Congress, enabling us to better grasp examples of change following sound treatment. It was recorded in Paris, on 12 August 2025.
Interview
My name is Luc Verrier, and I have been working in the Multimedia and Sound Department of the National Library of France for over 30 years. I am a project manager for the digitisation and digital preservation of audiovisual documents. In 1996, I worked on the transfer and initial restoration of the 1932 Cairo Arab Music Congress, and in 2014 I had the opportunity to work on the restoration of its complete recordings.
I have chosen to present a piece from this collection. It is a recording of Moroccan music, performed by the Nouba de Fès, the ensemble of Omar Al Ja’idi. The title of the piece is : “Travel the world, you will grasp its secrets”.
It is a completely traditional instrumental ensemble consisting of two violins, a rebab, two uds, a small tambourine and three singers. I was captivated by the title of the piece. One could rather say, Travel through the sound of Arabic music, and you will grasp its secrets.
This recording was made on 16 March 1932 for the Gramophone Company under the His Master Voice label. The sound engineer in charge of the recordings was Georges Walter Dillnutt. He was born in 1883 and died in 1937.
I suggest you listen to it, perhaps starting with an unrestored version. It is possible to discern the type of microphone used by Dillnutt in some photos of the Cairo Congress recording. It is a Western Electric 394, a very high-quality condenser microphone that was a benchmark at the time. This microphone had excellent technical characteristics and was capable of recording frequencies ranging from 50 Hz to over 6 kHz. It is thanks to the use of this type of microphone that we have recordings of such high quality.
Of course, we can highlight the virtuosity of the instrumentalists and singers, but we can also highlight the great mastery of the British gramophone operators in recording. As you may have noticed on the first recording, the surface noise of the disc is very present. This is inherent in the techniques used to engrave the disc. It is an electrical recording engraved on a flat wax disc. The wax on which the groove is engraved rotates at 78 revolutions per minute.
Once sent to the pressing plant and after an electroplating stage, we obtain a 78-rpm disc by pressing. All the crackling we hear comes from the surface noise of the 78 rpm disc. The first stage in transferring this collection consisted of digitising all the discs. All of the discs were cleaned, played and digitised using modern playback equipment. A master copy, known as a preservation master, is stored in the Bibliothèque Nationale de France’s digital preservation system.
These scans were made in high definition. Based on this master copy, various restoration phases were carried out. The first stage of restoration consisted of declicking and de-crackling all of the discs. Thanks to this first step, it is possible to focus our attention on the useful signal, the singing and the instruments. I now invite you to listen to the original version, our original master, and the restored version that you can hear in the reissue.
As you can see, the restoration allows us to focus our attention on the music and the musicians’ intentions. Furthermore, the fact that we have almost completely removed the surface noise from the 78 rpm disc allows the musical signal to be revealed even more clearly. During this first phase of restoration, clicks and crackles were removed automatically. Various pops were removed manually. This operation requires a great deal of time and care.
In 2014, a second phase of restoration was carried out. We carried out various manual filtering and restoration processes in order to remove a number of annoying noises. This also allowed us to homogenise the levels. We realised that on almost all of the discs, there was a humming noise in the low frequencies. This was barely audible, if at all, on the playback systems of the time.
This type of interference probably came from a filtering defect in the recording and engraving amplifiers. Here is another example of interference frequency that we found on some discs around 200 Hz and its harmonics. On this recording, it is interesting to note that the musicians took care to record certain instrument tones and an acoustic “A”. This acoustic “A” at 435 Hz allows us to confirm that the 78 rpm discs are spinning at the correct speed. As I mentioned earlier, some noises originate from the recording device.
Here is an example of cyclical noise in the low frequencies due to a mechanical problem. Also originating from the recording device, here are resonances in the high frequencies of the engraving stylus. Thanks to manual filtering, all of these frequencies have been greatly reduced. When listening to the 333 sides of the records from the Cairo Arab Music Congress, we realised that there were quite a lot of unwanted noises. Our goal was to remove or reduce them.
Here is the restored version. It may have been an object falling, a door slamming, but there were also motorised vehicles passing by. You can hear these rumblings in the low end of the spectrum. Finally, very slight filtering was applied to the recordings from the Cairo Arab Music Congress to provide sufficient bandwidth while preserving as much useful information as possible. No equalisation or dynamic compression was applied. The recording levels were adjusted on the different tracks to make the listening experience consistent across all the discs.
This work has resulted in the restoration of an authentic archive document containing over 18 hours of music, faithful to the original phonographic recording and intended to serve as a reference for researchers, musicians and enthusiasts. Finally, I invite you to listen to the fully restored track from “Travel the world”.
Enjoy!
FIND OUT MORE
France Inter, Série “Les oreilles d’or,” Épisode 8/10 avec Luc Verrier: Comment redonner vie à de vieux enregistrements? 4 min., 28 décembre 2022, Radio France.