To reproduce, go to the referenced URL and click "Sounds of the Ridings" in the left hand column. Then click on one of the three regions of Yorkshire to hear a sample dialect from that place. The audio should play, but doesn't.
This does not appear to be a JavaScript related bug. This page fails on FireFox too. The code appears to try to invoke a method called 'play' on the embed object, and in WebKit we don't appear to provide this property (nor does FireFox). If I'm understanding this correctly, then if we wish to make this work in WebKit I think we'd need to expose API on the embed element to allow users to control playback. Of course, an alternative would be to fix the content to support HTML5 audio elements. As such, it seems possible that this is WONTFIX. I'm not sure what the right component is for this, I'm going to try Web Audio in the hope that this is appropriate, and if not that it might draw the attention of an audio expert to shuffle it on in the right direction. :o)
This is unrelated to the Web Audio API
<EMBED NAME='CS995277342254' SRC='sounds/JB.mp3' LOOP=false AUTOSTART=false MASTERSOUND HIDDEN=true WIDTH=0 HEIGHT=0>
The embed object will have whatever methods the underlying plug-in exposes. On my system, QuickTime is loaded to play the mp3 file, but QuickTime doesn't expose a method called 'play()', and the author explicitly sets the autostart attribute to false, so no audio plays. QuickTime does expose a method called 'Play()' (note the capital P), but this is of course plug-in specific. I don't think there is a WebKit bug here.
I think that this dates back to times when EMBEDs had behaviors of their own, and didn't rely on plug-ins.