If it’s on only these five lines, I would say the answer is, the sound of a woman’s singing and playing. But before these lines, the poem was an entirely different vision. If I looked at the poem as a whole I would say the answer is the vision he saw of Mt. Abora. As it was an opium experience, I would think if I went through it I would want the other person to somewhat experience what I went through as a whole, not the one excerpt. Hope that all makes sense