Why the new emphasis on music (l.43)?

I don't see any references to music in this scene. 

it's from line 40

Portia orders music to be played for Bassanio, and one of her servants starts to sing a song in which the rhymes all rhyme with lead. Portia first begs Bassanio to wait at least a month, hoping to spend time with him before he chooses among the caskets. When he refuses to wait, she plays music for him. Some scholars have noted that each of the rhymes of the song rhyme with lead, thus providing a subconscious hint.