Just make it an "event" that doesn't constantly call for focus like an onmouseover() or something like that. Don't forget to stop sound onmouseout(). You have to also make sure it doesn't push you over the size limits.
My (yet to be released) new signature has event related sounds for "button clicks" and "hovers". With the sounds I went over the limit, so I had to convert all of the button "bitmap" graphics to "vector" graphics to keep it in check. Not quite as nice but I obtained more depth with the event sounds.
JC