and why "the sound" is used here, not "the sounds"?
Answer from a Native speaker
Here, "the sound" is used instead of "the sounds" because they're talking about "the sound" as a whole and in general, and not individual sounds from the instruments. Ex: I love the sound of the wind chimes near the door. => as a whole, in general Ex: I love the sounds of the wind chimes near the door. => each individual sound from the instrument Ex: I could hear the sound of whispers coming up from my bedroom window.
1/2 STEP LEARN