Someone who tends to use a combination of loud and often jarring words or sounds: When Jacob was delivering his political speech, a woman from the audience interrupted him with a critical comment and as a result, he lost his temper and suddenly became a cacophonist who yelled at her to sit down and to shut up!

The members of the orchestra were a bunch of cacophonists producing a lot of racket as they were individually tuning their musical instruments before the conductor started rehearsing.