Analyzing the Word Cacophony in Context

In the following excerpt, the author explores the theme of isolation:

"Surrounded by the cacophony of the bustling city, she felt like a ghost, drifting through a world alive with sound yet completely muted within her own heart. Each day passed in a blur, the vibrant hum of life around her contrasting sharply with her own quiet despair."

What effect does the word cacophony have on the sentence?