Abat-son

An abat-son (usually plural abat-sons) is an architectural device constructed to reflect sound in a particular direction. Typically it takes the form of large louvers which direct the sound of church bells from a bell tower toward the ground.

In general use, any louvers in a bell tower are commonly called abat-sons, whether they are designed to redirect sound or merely to prevent ingress of water.

The shade designates a small canopy or the set of blades inclined downward and outward disposed in the ears of the steeples and belfries. The blades, usually louver type and fixed in a frame frame, are usually bare wood or covered with metal, slate or lead.

They usually garnish the bells of belfries or belfries, for:

prevent rain and snow from entering their interior;
ventilate the carpentry;
return the sound of the bells to the ground.
This technical term of architecture appears in the nineteenth century, these blades were until then designated by the term of shelter.

History and style
The shades are often inserted in the twin bays on each face of the steeples, more rarely in the skylights of the spiers of the steeples. These bell-shaped bays are typically flanked by columns with capitals and decorated with archivolts in Romanesque architecture, openwork intertwined in Gothic architecture. Abat-son develop especially from the thirteenth century, they are often decorated with openwork, sawtooth at their lower end, or embossed on lead.

The existing shades are being renovated when the wood is deteriorated or their zinc or lead coating is corroded. They are sometimes made of composite material to be radio-transparent to radio equipment (type antenna-mobile phone relay) and equipped with anti-volatiles nets or screen protectors to close the access of the steeple to pigeons or crows.

Source From Wikipedia