Hey Bello,
Hope you're doing well! Actually, I'm not sure I understand what you're asking about. Is it HTML5 audio and stop event? (In this case, I can't see how it deals with Node.js) Or maybe you're asking about how to stop processing the request if the client (browser) breaks the connection, e.g. a user goes to another page. I don't know.
Anyway, can you elaborate this? And maybe add some code which you're struggling with.