Not possible with plain HTML. You would have to use Flash to do that in a cross-browser compatible way. However, I’d really recommend to scrap that idea entirely and don’t play any sound on your website except the visitor asks for it (i.e. leave them a choice). This is annoying to many people and many people switch off any sound (if they can) without pondering about it for a second. Also, although possible with Flash it’s the worst way you could go as this would be yet another website where Flash is misused for a useless effect that’s there just for the effect, plus, for that reason there are most likely gonna be some serious accessibility
So in a nutshell: Just don’t do it.