I am aware of this problem and it will be fixed in the next version.
The problem seems to be caused by the way the browser plays the audio file of the <audio/> tag. Once Chrome plays the audio track, the current time is not moved at the start of the audio file, but it stays at the end. That's why when we try to play the audio once more, it is not played.
After extensively testing and trying different things with the <audio/> DOM object in Chrome, I found a way of making the audio file play more than once. Here is the JS code. Place it below the ScriptManager of the page where the RadCapthca resides, and see if it will work:
Let me know if you still experience problems.
the Telerik team