I didn't ask specifically about earplugs, but they make you turn your pockets inside-out and don't let you bring anything into the test center except your ID and the key to your locker (+ a marker and two sheets of plastic to scribble on).
At the stations they have headphones and earmuffs, so you could either wear the headphones the whole time or wear the earmuffs for even more sound blocking - bringing your own earplugs is really unnecessary.