As was mentioned in the previous post, Montag has three television walls in his parlor. Mildred, Montag's superficial wife, is infatuated with the interactive television shows and spends the majority of her day watching them on her parlor walls. The parlor walls are essentially massive television screens that are the size of each wall. At the beginning of the novel, Mildred petitions Montag to buy a fourth parlor wall. However, Montag explains to his wife that he simply cannot afford the fourth wall because it costs nearly one-third of his annual salary. Mildred's addiction to her parlor walls is typical in Bradbury's dystopian society where individuals are constantly entertained. Mildred values her interactive television shows more than she does her own family. Her addiction to the parlor walls contrasts with Montag's intellectual pursuits throughout the novel.
The parlour consists of three interactive television screens, each the size of the room's wall. Mildred inserts a seashell (we might describe this as the earbuds used with an Ipod) into her ear and reads a small part in the script written for each interactive show.
Montag's TV room does in fact have three full walls and his wife does want a fourth. Her desire to have the fourth wall is for total immersion in the TV realm. Shows actually engage the viewer in the show, think the ultimate reality show. The person sitting in his or her individual TV room gets involved in the show.
So Montag's wife, thinks of her TV show people as her family. She fills her life with the shows that she watches, so the TV set-up is very important to her.
Montag's living room consists of three walls that are TV screens (they haven't yet paid off the third wall and they are very expensive). Montag's wife already wants a fourth wall put in so she can be absolutely immersed in the lives of others--presumably to forget how miserable her own life is?