Google Chrome	67.0.3363.0 (Official Build) canary (64-bit)
Firmware Version	Google_Samus.6300.276.0

For now, go to Chrome://flags > Enable Experimental accessibility features to get the latest version of STS. In the future, this step won't be needed.

Steps to repro:
# Get STS speaking on any text 
# Start typing anywhere, this could include within the open tab or another program like Text 
Expected: STS stops speaking
Actual: STS continues speaking

For parity, I checked ChromeVox and if you start typing text while it speaks, it will start reading the letters you've typed. However, ChromeVox reads typed letters while STS doesn't so it's not a perfect comparison.