In Edgar Allan Poe's The Masque of the Red Death, how do the chimes of the clock affect the guests?

In his short story The Masque of the Red Death, Edgar Allan Poe devotes considerable time to physical descriptions of Prince Prospero’s abbey, specifically, the adornments of the seven rooms that collectively comprised “the imperial suite.” Each of the seven rooms features a different color. It is the seventh room, decorated in black with windows the glass of which were “scarlet—a deep blood color”—that contains an imposing clock, described by Poe’s omniscient narrator as “a gigantic clock of ebony” with a pendulum that swings, as the narrator notes:

“. . .to and fro with a dull, heavy monotonous clang . . . a sound which was clear and loud and deep and exceedingly musical, but of so peculiar a note and emphasis that at each lapse of an hour, the musicians of the orchestra were constrained to pause, momentarily, in their performance, to hearken to the sound; and thus the waltzers perforce ceased their evolutions; and there was a brief disconcert of the whole gay company; and, while the chimes of the clock yet rang, it was observed that the giddiest grew pale, and the more aged and sedate passed their hands over their brows as if in confused revery or meditation.”

Prince Prospero’s clock plays a prominent role in the progression of Poe’s story. The swinging pendulum, reminiscent of the giant pendulum from his short story The Pit and the Pendulum, represents an ever-foreboding presence amidst the merriment that defined the prince and his friends’ carefree demeanor. While the music plays and the partyers dance and the magicians and “fools” entertain the assembled elite of this fictional society, the gaiety is interrupted every hour by the clock’s ominous chimes, each occasion immediately followed by a resumption of the merriment.

It is the clock’s chiming that, at the stroke of midnight, signals the story’s most prominent and irreversible shift from its emphasis on partying to an atmosphere of impending doom. Once again, as Poe’s narrator describes the scene:

“ . . .now there were twelve strokes to be sounded by the bell of the clock; and thus it happened, perhaps, that more of thought crept, with more of time, into the meditations of the thoughtful among those who revelled. And thus too, it happened, perhaps, that before the last echoes of the last chime had utterly sunk into silence, there were many individuals in the crowd who had found leisure to become aware of the presence of a masked figure which had arrested the attention of no single individual before.”

The chiming of the clock, as it had regularly, every hour on the hour, causes a momentary lapse in the debauchery and gaiety that has stood in stark contrast to the wide-spread misery occurring outside the castle walls. This time, however, it is different; this time, the ominous tone that has descended upon the partyers with the clock’s chiming is different. It is accompanied by the realization that a masked  intruder walks among the gathered throngs and that this interloper represents a threat to the tranquility and security the revelers had enjoyed. In short, the chimes affect the guests by interrupting their fun and replacing the light-hearted atmosphere that otherwise prevailed with an ominous sense of foreboding.