Ok so I did a bit of experimenting with the issue.
1: Audio cuts out for the whole computer due to this issue, tested it by listening to music on winamp during a game and the music cut out.
Alt-tabbing to winamp would recover the music after about 5 seconds, alt tabbing back into the game would then break sound once again.
2: Turning on the Dolby 7.1 sound option in sound instantly fixed the audio then turning the Dolby 7.1 sound option back off still fixed the sound issue.
3: Checking the My Documents Overwatch logs reveals in the info that for some reason the sound was set to 0 by some event then back to the usual volume, this could be a record of what is going on I am not sure.
So whatever is going on in game it can affect the sound of your entire computer if the overwatch game is the focus and changing focus will make the sound work again temporarily.
That turning on Dolby 7.1 and then turning it off seems to refresh something that causes the audio issue and seems to fix it.
So the temp fix to solve this issue to if it happens in game go to your OPTIONS then go to DOLBY 7.1 and turn it on and off to fix your audio till the next time it happens.