Thanks for the report. The audio pauses likely because you have the pause audio while ChromeVox is speaking set in the ChromeVox options page.

Could you provide a little more detail about the audio file you played? I tried to reproduce on Youtube, but am not seeing a crash.

I can reproduce this problem by going to soundcloud.com/, and play the audio file... or go to youtube.com to play a video. If I continue to navigate with Chromevox; the audio stops,--instead of Chromevox keeping the audio playback intact,--just like earlier versions of Chromevox via earlyier versions of Chrome OS.
I placed the option for playing playback mode to nutral via the options.
The clue is: A slight delay,--when a Chrome device is idle!
Common issues with Chromevox itself is the following:
Chromevox taking up memory on your device
Broken sourcecode files
Broken scripts
Broken Features
Memory Leaks
Taking up too much processing power
Corrupt system files inside Chromevox itself
And more
You can fix this problem by adding more memory to your device.

Chrome 65.0.3299.0

I am not able to reproduce this issue.
If you are able to reproduce this issue with Chrome 63 or later, please reopen the issue and give the exact URL and keys to press to make ChromeVox crash.