Along those lines, but no human voice, just a loud beeping noise.
Until today I thought it was what you suggest above, but today the PC wouldn't do anything, and when I closed the browser (firefox) and re-opened it, the bloody thing was still there.
Malwarebytes has now opened and done a scan with no problems detected, so I will assume all is OK, and will send a message to the Wordpress blog owner that he has this adware problem, as it only appears when I browse his blog (if you're curious, it's aeolipera.wordpress.com.
Thanks for the speedy response.