A bug (I think) in the audio control: There seems to be a bug in the audio control. In the attached file go to page "External anatomy". The Anterior External Stack on this page has several layers each of which describes a chamber or vessel in the heart. Each layer has an audio description which is played when you click the 'commentary' button. When you go to another layer by clicking on another chamber or vessel, the audio for the layer that you're leaving plays again without any apparent trigger. It doesn't happen if you don't play the audio when you're in that layer and it doesn't happen if the audio is still playing when you move to another layer.

Thanks for logging this issue. It has been fixed.