How does Melchor utilize the motif of sound within Chapter VII?

At one point in the chapter, Melchor refers to the way in which the women's conversations as they gather on porches across La Matosa sound. More importantly, however, the narrator states that whenever the women's conversations die down and it gets quiet enough, music from the brothels on the highway can be heard. By differentiating between these two sources of sound, Melchor again underscores the idea that the townspeople are divided and have yet to find a way to come together as one group of women living and working in La Matosa.