The story opens:
"Jim and Irene Westcott were the kind of people who seem to strike that satisfactory average of income, endeavor, and respectability that is reached by the statistical reports in college alumni bulletins."In other words, we have an average family. The story ends with a "suave and noncommittal" radio announcer giving the news: a train wreck, a hospital fire, and the weather. While severe and devastating to the people it's happening, likely it's a typical day's news. This is the frame within which he relates his extraordinary tale.
The Westcotts buy a floor radio*. It initially intimidates if not frightens Irene. She even hides it away. Eventually she listens and hears another layer of noise. They fix it.
Irene hears voices and gets Jim to hear. Jim yells at the device to see if he can be heard as well. He cannot. She recognizes the voices of neighbors. Some of what they say is scandalous and horrifying. When they attend parties, Irene cannot see her neighbors the same. They've lost their gloss, their human decency.
The radio's gossip consumes Irene. She begs Jim to intervene in other couples' problems. He won't, but he will fix the radio. This time the repair works, but the fix is expensive. Jim confronts Irene over unpaid bills. They have a spat equivalent to their neighbors'.
Here's where the frame fits in. With plenty of dirt on each other, they are no better than anyone else, have no justification to feel morally superior. The Westcott's tale seems more relevant with our radio the internet, flooding the information world with our sins, with many coming to the rescue or condemning their neighbors.
Cheever adds a nice duality of perspective, which is demanded of its readers to have a full understanding: Some readers will identify more with Jim, some Irene, while other readers will empathize with both.
* This is 1947-ish. Household radio technology is still shiny even if it had been around for twenty-odd years, as can be seen by a $400 charge to repair the apparatus. Something about new technologies gives it a paradoxically mythological air. Twilight Zone did a similar story where a man witnesses, on his television, the future crimes he will commit.