When I look at the console after clicking the goose (Safari) I get the error:
> [Error] XMLHttpRequest cannot load http://www.northernchildrensbookfestival.org.uk/widgets/ncbfballoon.hyperesources/honktimed.mp3?. Origin http://ncbf.tlmultimedia.co.uk is not allowed by Access-Control-Allow-Origin. (soundtest, line 0)
I am no expert but that looks like a cross domain violation.
Are you trying to load the file from the other site..?