The "Jewel Voice Broadcast" is a Artifact from the lost ancient magic technology, commonly used as a message broadcasting system to the general public.
The true nature of the "Jewel" is unknown as its from the Lost Ancient Civilization, and the only place to get them is from a "Dungeon".
The only information that have been uncovered regarding them is that the "Jewel" are actually the "Dungeon Core", and that utilizing Water & Wind Elemental Magic on them causes them to take in the scenery around them and project through the receivers. Rest of its functions still remain a mystery.
The Jewel Voice Broadcast is the magical equivalent to the television camera. Receivers or viewers must be on the same 'magical wavelength' to be able to receive whatever images and sound the Jewel Broadcast Orb transmits. For example, Naden Delal had purchased a broken receiver and made it work with her electrical powers. Since it was bought from the Gran Chaos Empire, it could only receive programs from that country and not from other nations, such as Freidonia.
People who are skilled with water magic, such as Excel Walter are able to create viewers on their own, such as being able to transmit Kazuya's declaration of war at Fort Altomura. In most cases, a water-based viewer such as the Plaza Fountain in Parnam, are used to inform and entertain the masses.
Since Jewel Broadcast Orbs are actually dungeon cores, most nations have one or two of them. The Gran Chaos Empire has many of these orbs and therefore use them as part of negotiations with other countries. The Republic of Turgis were given an orb during the negations of the Tripartite Medical Alliance.