Foroux, I have ran across a couple of sites where I couldn't find the mute button on the site and it was irritating, so I understand what you're saying.I always have my speakers muted, so it's something I haven't noticed in the wild. It would be pretty jarring if I didn't mute sound, especially on sites where I'm not expecting music to play. I guess if music is a must, just make sure there's an easy way to mute it on your site.
@JackD I also always have music playing when online and can see how it would drive me crazy for a site's music to interfere with that.I don't care for it. When online browsing, I usually have music that I like playing in the background and if the website in question interfered with that, then I would probably not stick around on the site or return to it in the future.