DC Audiovisuel is proud to have contributed to the Gonbessa 5 expedition, operating alongside with Les Gens Biens Production. So we've reached Marseille to meet the crew who achieves to complete successfully this world premiere adventure.
A human challenge
« If you stay 3 hours at 120 meters, you’ll need one day before you can reach the surface » said Laurent Ballesta.
Submarine photographer Laurent Ballesta and his three companions Antonin Guilbert, Thibault Rauby and Yannick Gentil take on the Mediterranean Sea unexplored depths.
In order to do this, the four experimented divers lived in a complex of 3 compression chambers installed on a barge, with barely 10-meter square living room (bedroom 5 m², shower 2 m², diving bell 1 m²), a mission very similar, as for live conditions, gravity excepted, to what astronauts can endure in the ISS.
This complex has to be maintained at a 140-meter pressure (13 times atmospheric pressure), filled of a 90% helium composed gaz. An airlock has been used to give them meals.
This pressurized environment allowed deeper and longer diving sessions never done before at this depth, without the decompression constraint. Thus, the four divers reached up to 6 hours diving time by session in places that had never been explored before.
« The goal is to show that there is still a wonderful Mediterranean Sea, some lost paradises, secret oasis when you dive over a certain depth. There are so much animal species to discover and describe for the first time » continues Laurent Ballesta.
A technical challenge
This whole 28-day expedition has been recorded and filmed, in order to produce a 90-minute documentary for Arte Channel within the next year.
Technically, it was a huge challenge. Because of the helium atmosphere in the room, it was only allowed to use up to +24V (48V phantom strictly forbidden) power. The living space was reduced to the strict minimum, leaving just few spaces for the microphones, Osix shockmounts and RF antennas.
A control room was set up outside, on the barge, and linked to the pressurized complex via multiples stuffing boxes, running audio and RF wires. Each diver was equipped with one lavalier pocket transmitter completed with one handheld radio mike. Many additional microphones were placed too, giving a full audio experience of this adventure. Claustrophobic, be advised.
Because of helium atmosphere, divers' voices were pitched up, making it more difficult to understand each other. In such environment, the human ear fails to identify clearly the origin of audio sources.
With the help of IRCAM, we developed a system which allowed to process in real time all of the divers' voices, correcting pitch and throat length, in their own audio return, as well as in the communication system to the outside.
With no more than 3 ms latency, the control room was therefore able to real time adjust tone and pitch of the divers' voices, a world premiere in the sur-pressure diving world, making the life inside the complex much easier.
In order to wait until the release of the documentary, regarding the many daylies to process, the Gombessa Team has been broadcasting on Youtube a vlog series, almost one per day of expedition.
For having provided all the sound equipment and co-designed the whole audio setup, DC Audiovisuel was associated with a special event covered by the press for the exit, after 28 days of total isolation. This event allowed people to discover this exceptional expedition and highlighted the diving world.
« The sea is everything. It covers seven tenths of the terrestrial globe. Its breath is pure and healthy. It is an immense desert, where man is never lonely, for he feels life stirring on all sides. The sea is only the embodiment of a supernatural and wonderful existence. It is nothing but love and emotion; it is the 'Living Infinite', as one of your poets has said.
Ah! sir, live--live in the bosom of the waters! There only is independence! There I recognize no masters! There I am free! » Jules Vernes