The speaker(s)
The speakers, who "wear the mask," are represented as a collective identity via the first-person plural form ("we"). They dissemble in order to conceal their anguish, and while they are unhappy about the need to hide their true emotions, they would rather the rest of the world be oblivious to the discontent hidden behind their masks.
The world
The rest of the world—comprised of those who do not "wear the mask"—does not understand the complex psychological processes behind this act of dissimulation. The collective "we" voice of the poem observes a significant gap of understanding between themselves and the non-masqueraders.