In watchmaking, striking refers to any system that automatically sounds the time by striking a gong or bell without the wearer's intervention. The fundamental distinction lies between mechanisms that sound on demand — minute repeater, activated by pressing a pusher or slider — and those that chime autonomously as time passes.
Among the latter, sonnerie au passage is the most direct form: a hammer strikes a gong every hour, precisely as in the MeisterSinger Bell Hora. Some calibres, such as that in the C1 Bel Canto Classic, add a dedicated module with an on/off indicator visible on the dial, because keeping a sonnerie active drains the power reserve rapidly. Grande Sonnerie scales this logic: it chimes automatically every hour and quarter hour, with distinct sequences for each. The Grande et Petite Sonnerie — mastered by a handful of manufactures, Philippe Dufour among them — adds the ability to switch from full sonnerie to hours only, and complete silence. Bvlgari manages internally a portfolio reaching configurations with four hammers, which is rare even for a major maison.
A critical component in any striking mechanism is the striking regulator, also called governor: it is the cam-governed wheel that controls the speed of the striking sequence. If the regulator is poorly designed, the blows overlap or arrive with irregular delays. In Patek Philippe's Supersonnerie calibre, this element was redesigned precisely to eliminate the background noise that degrades acoustic clarity. The shape of the gong — straight, curved, or tube-shaped as in the Otsuka Lotec No.9 — substantially changes the timbre and sound projection.
The term striking also encompasses less traditional applications. In Théo Levaltier's project, the jumping hour is connected to a mechanism that strikes the gong at the precise moment of the hour change; a side selector permits a silent mode in which the hammer vibrates without producing sound, useful in formal settings. Zenith, finally, applied the name Striking 10th to a chronographic function: the central hand completes a full rotation every ten seconds instead of sixty, readable on a 0–10 scale on the dial, leveraging the 5 Hz frequency of the El Primero calibre. It is not a sonnerie, but the logic of the name — striking a precise time subdivision — echoes the striking vocabulary.