There is a vast difference in size between comets and the objects that form meteors. Meteors are typically at an altitude of 100km, the upper reaches of our atmosphere. The nucleus of a comets is city-sized, as we have already seen, and the head of the comet is big enough to hold several earths, typically. Comets are moving at a similar speed, though usually a bit faster. As in grade 3, it's appropriate to talk about sound in space at the upper grade levels in elementary school.
Space is airless, so there is no way for sound to be transmitted.
A space odyssey are accurate in this respect. But comets aren't in our atmosphere, so we can't hear them. There is empty space between us and the comet. To answer this question for the kids, it's a good idea to help them get their bearings in the solar system. A gymnasium is a good place for this.