I would like to know what "At once a string of quick, light beats prepared the room, gathered our attention, ecstatic, simple and single-minded." means in the following sentences:
And then the music stopped. The record had come to an end; the low crackle of the speakers could be heard between the suddenly naked chatter of the crowd. We looked at each other, bemused, in anticipation. A new record was placed on the deck by a gangly boy in green bell-bottoms. At once a string of quick, light beats prepared the room, gathered our attention, ecstatic, simple and single-minded. And before we knew it, Blondie’s siren voice had filled the room, sending a rush through us. We didn’t know the words, not a single one, but we understood everything about ‘Heart of Glass’ – all its elation, its decadence, the pleasure of self-indulgence. We made our way through the crowd to the middle of the room, where we dissolved ourselves in her voice, in its high flight, in the rising and falling melody, in the motif of the beat, the beat that was there from beginning to end and begged to be followed. Our heads spun along with the record. Our bodies became instruments of the song, extensions of it, and we formed as one, dancing in a triangle, swaying from side to side as if possessed. When the song had ended, another one began to play, one just as good and catchy and seductive, and we gave ourselves to it. It was as if someone had taken us all and placed us on a platform on top of the world. We danced until sweat ran down our backs and foreheads and we could no longer catch our breath.
In this novel which is set in the 1980's in Poland under the socialist regime, where homosexuality was socially unacceptable, the protagonist Ludwik (a university graduate) left Poland in 1981 to live in the United States of America. And he remembers what it was like back then in Poland, where he went to the birthday party of his rich friend Hania. In the party room, quick and light beats filled the room.
In this part, I wonder what "At once a string of quick, light beats prepared the room, gathered our attention, ecstatic, simple and single-minded." means. What does it mean that the beats "prepared the room"? (Is it close to a warm-up?) And, does "ecstatic, simple and single-minded" modify the people at the party, or the beats themselves? And what would it mean...?
I am an English learner from South Korea, so thank you for your patience in advance as I may not know obvious things. I would very much appreciate your help. :)