"However, unfortunately, in many, many cases, bar mitzvah boys don’t lain loud enough, don’t pronounce the words clearly, swallow parts of words, or are unfamiliar with the basic laws of dikduk and trop." (source)

"When we read Torah in the synagogue, we are not simply commanded to recite it, rather to sing it with special chanting motifs called tropes (musical symbols) of cantillation." (source: login required).