Classical Syriac keeps two pharyngeal consonants, written by heth and by the sixteenth letter. They are made deep in the throat and they have no counterpart in most European languages, which is why descriptions of them in English reach for comparisons that do not quite work.
In the living languages the pharyngeals have been under pressure for a long time. Turoyo and the modern Aramaic dialects of the Assyrian and Chaldean communities have handled them differently from one another, and in a number of them the classical distinction between heth and he has narrowed or gone. The letters are still written, because the writing follows the classical spelling, so the page preserves a contrast that the ear no longer always finds.
This is worth stating carefully rather than as a decline. The churches that use Syriac read it aloud, and the liturgical reading maintains distinctions the spoken dialects have lost, in the same way that the reading traditions of other liturgical languages do. Which pronunciation is correct is not a question with a single answer: the eastern and western reading traditions already differ from each other, and both are old.
What the atlas can say is narrower and firmer. The letter is the eighth of the abjad, it carries the numeral value eight, it writes a pharyngeal in the classical description of the language, and how it is sounded today depends on which community is reading and in which tradition.