Supersonnerie is an Audemars Piguet patent, not an autonomous complication type: it's an acoustic system applied to existing minute repeater and chiming complications, designed to transfer the sound performance of antique pocket chronometers to the wrist. Presented in 2015 with the Royal Oak Concept RD#1, it is the result of eight years of research conducted with the Federal Polytechnic of Lausanne.
The fundamental principle is simple to understand, difficult to implement. In traditional repeaters, the gongs are fixed to the movement plate: the plate is rigid, absorbs vibrations and disperses them into the case metal. Here instead, the gongs are anchored to a separate soundboard — made from a special alloy, in some models from sapphire crystal just 0.6 mm thick — that acts as a resonating diaphragm. Vibrations propagate through this element before reaching the case, resulting in volume and clarity comparable to an acoustic stringed instrument.
The second intervention concerns the escape regulator. In conventional repeaters, the repeater train escapement often generates mechanical noise overlaid on the strikes. In the Supersonnerie system, the regulator incorporates a flexible anchor that absorbs impacts and suppresses those parasitic noises, allowing only the tone of the gongs to be heard. It is an operation of subtraction, not addition.
The case geometry contributes decisively. In the RD#1 the caseback is composed of two layers: an inner one with calibrated openings and an outer one in sapphire, which closes an air chamber between the two levels. This chamber acts as a secondary resonator. The solution conceptually recalls the construction of 19th-century marine chronometers, where the case itself participated in sound amplification.
From the bench I have listened to several specimens with and without this technology. The difference is real and measurable in listening: the sound is more projected, less muffled, with a longer resonance tail. I cannot judge how much marketing and how much physics accounts for that result, but the physics is there.
Supersonnerie is today also present in the AP 1000 caliber of the Code 11.59 Ultra-Complication Universelle RD#4, where it coexists with a Grande Sonnerie among the twenty-three complications of the movement.