For me, every page has a goal, which is usually either:
1. Guide the user to another page or
2. Provide action/content of value to the user
If sound does not serve either of these goals, it is at best a non-critical accent to the site, and at worst (and I´d say more commonly) a distraction that can push users away.
HomeAndBodyEssence3
As a frequent online shopper myself, I tend to hit the back button almost immediately whenever I go to a webstore that plays music. I think it is extremely annoying and intrusive and a lot of times, the unexpected sound startles me. I tend to steer away from websites that have too many flashing pages also.