Sometime, as Disney fans, and fans that visit the parks a few times a year, we tend to know almost everything that's going on in the parks. This includes not only the lyrics to various music, but also the spiel given at various attractions. This is especially true for the several attractions such as the Haunted Mansion and Tower of Terror, and to some extent, Jungle Cruise. I've often seen other guests who recited along with the audio tracks on these attractions, and they were certainly loud enough to be heard by the immediate guests surrounding them.
Unfortunately, we also tend to forget that there are folks who are going on these attractions for the first time. These guests want to hear and experience what they paid for. They didn't pay to hear other guests reciting to them the audio tracks of the attraction. Not only can this be annoying, it is also distracting. What is worse is guests that can't just shut up during such attraction. I've been in the library of ToT attraction, and had people yapping away while the Rod Serling-like voice was setting up the whole attraction for the guests. Not only is this annoying, it also made it difficult to hear, which ruins the whole set up of the attraction. The same is true for the stretching room in the Haunted Mansion. Oh, I've been known to utter a few words along the way here and there (".... to find a way out!!"). But to recite the entire spiel and ruin it for other guests?