better browser support for sounds

[w31rd0]

Sounds may not work in all recent browsers. For example Opera crashes after second click.

[w31rd0]

Opera 11.10 seems to fix the crash issue (DSK-331651). But on the other hand it breaks hidden="true" behavior. One obvious fix is to remove hidden="true" and style embed with "width:0; height: 0". Need to check this will work in other browsers.