When he returns home from work, Montag briefly think about buying an “audio seashell broadcasting station” Why does he think about this?

Mildred paid no attention to Montag when he got home from work because she was too busy listening to people with her Seashell earplugs. If he bought a braodcasting station he'd be able to talk to through her earplugs.

Wasn't there an old joke about the wife who talked so much on the telephone that her desperate husband ran out to the nearest store and telephoned her to ask what was for dinner? Well, then, why didn't he buy himself an audio-Seashell broadcasting station and talk to his wife late at night, murmur, whisper, shout, scream, yell? But what would he whisper, what would he yell? What could he say?