If you are using a browser with JavaScript / Flash enabled you can have all manner of content thrown at you. It used to be common practice in the olden days for websites to have an accompanying sound track. However as peoples tastes in music are so varied it has become very unfashionable and most sites have abandoned the practice. It can also take a lot of bandwidth to shove audio down the line. However, some companies use the technique to push audio adverts via your browser.
Edit: I'll just add that the adverts are not directly from the WP site but from one of the many sites that pass on advertising through third party sites. WP probably has very little control on the content of ads that get pushed with its site content - either visual adverts or audio based. This has also become a malware vector too with popular "legitimate" websites unknowingly passing on adverts which have been specially designed to contain malware intended to do nasty things to your computer, conscript it as part of a botnet, spamnet etc or install keyloggers to steal your online banking details or personal documents etc. Even if your computer is fully patched and all software up to date, the malware writers are now targeting what are called "zero day exploits" where they find vulnerabilities and take advantage of them before Microsoft, Adobe etc and the anti-virus people etc can fix / block the problems or release patches.
I've not had any audio adverts for years - not since switching to the oft mentioned Firefox with Ad Blocker plus, No Script and Flash blocker. I can selectively chose what content sites can throw at me. Especially important because I only have dial-up internet - these "crap filters" speed up web browsing enormously. They also make browsing much safer and far less chance of picking up something nasty from the internet.
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I've left WP indefinitely.