Basically the premise is there's this radio station that suddenly begins emitting a white-noise sound that causes everyone who hears it to feel immensely relaxed and happy.
I remember one early point of the plot involved a grocery store that went completely silent because everyone inside it stopped what they were doing and just stood there enjoying the "radio drug" (I think it was being broadcast via the loudspeakers). Later on, the entire city is completely still when people at home tune in and are so high/relaxed that they're even forgetting to eat. A scene where boy scouts show up to one family's house to try and save them (don't remember how they were unaffected by the radio). The story finishes with a TV broadcast of a reporter commenting on the bizarre phenomena who mid-sentence starts feeling relaxed and praises the radio station and encourages everyone else to give it a listen.
I read this back in high school for an English class and have been scouring the internet to try to find its name; every former classmate I've asked doesn't remember reading it either. Either my friends are as forgetful as I am or this is some false-memory level weirdness because I specifically remember reading it