Is HN Hacked?
I had HN open and the chrome tab showed the audio sign, and some voice was running as if someone is talking... is HN Hacked?
Are you running any browser extensions?
Check what sites permissions are, what can send 'notifications' to you and clear them out. That is a big source of these things.
Did you open the web developer console and capture the URL that is being loaded? If you happened to capture the URL's I would suggest saving the logs as plain text and emailing as an attachment to hn@ycombinator.com for dang to review.
What was the voice saying? If it was not understandable, why?
Was it some Text-to-speech feature in your browser maybe?
edit:
You may be able to find the audio file in your browser cache
UPDATE: turns out this is happening not only on HN in my browser, so definitely its from my side.
Are you sure it was HN, or some similar misspelled domain?
Which version of Chrome and OS?