Also this is something I should have asked originally and I feel kind of stupid for not asking. There is probably a headphones jack on the tablet / screen bezel. Have you tried plugging earbuds or headphones in here to see if the sound works in them? It's possible that the speakers themselves are faulty and not the actual sound device.
Ok, lets have a look at that driver. Open up the Device Manager and highlight the Intel SST Audio Device and right-click it, select Properties. That should bring up a windows with four tabs (General, Driver, Details, Events), it's likely the General tab is going to say This device is working properly since there were no exclamation marks in the main Device Manager window. Lets start at the Driver tab. Can you take a screenshot of it? This will give us the details of the driver itself. This is also where you can Roll Back Driver.
Before rolling back (I know it's tempting to just try it first), could we get a couple screenshots? That way we know where we are before we change anything. After taking the screenshot here, lets have a look at the Events tab.
This is going to give us our crumb trail so to speak. All events to do with this hardware will be logged here. If your assumption about Windows Update breaking something (though it apparently doesn't know that it's broken) it should show us the last things that went on. It sorts it from oldest events at the top to latest events at the bottom of the list. If there are enough of them, you are likely going to have to use the scroll bar to see the bottom of this list. Hopefully you are going to see events around the time of the Windows Update that started all of this. At least that's my hope. Can you take a screenshot of this? I'm hoping you'll see a series of events here that show that the old driver was removed and a new one installed. Or at least something pointing to the fateful day you lost your audio.
At this point with all the screenshots made, go ahead and give the Roll Back Driver button on the Driver tab a push (assuming the button isn't greyed out. After doing this (a reboot may be needed), does the sound work?
I patiently await your answers.