There are two kinds of trop by means of which the Ten Commandments are read. They are called ta'am elyon and ta'am tachton (lit. the "uppermost meaning" and the "undermost meaning"). The difference between the two is "musical" but not only musical.
Ta'am tachton is the regular trop of this passage as part of the Scriptures. The special trop - ta'am elyon - breaks up the sentences in a different way, joining
There are two kinds of trop by means of which the Ten Commandments are read. They are called ta'am elyon and ta'am tachton (lit. the "uppermost meaning" and the "undermost meaning"). The difference between the two is "musical" but not only musical.
Ta'am tachton is the regular trop of this passage as part of the Scriptures. The special trop - ta'am elyon - breaks up the sentences in a different way, making each commandment into one verse, and is used only in the public Torah reading, resembling the revelation at Sinai. As you noted, most communities use it only on Shavuot, the Festival celebrating God giving us the Torah.
See Chizkuni Shmot 20:2, see also Masat Binyamin chapter 6, Elya Rabbah 142:1, and Shulchan Aruch Harav 494:8.
