Mode: force_next
Version: 54.0.2820.2
Reproduction Steps: 
This behavior is exhibited any time Talkback is speaking in tho background. An example is when new apps are being installed or updated, and a user switches to a different window and is using Chromevox. When the Arc++ version of Talkback is talking, chromevox goes silend and it takes a few seconds after Talkback stops talking for Chromevox to talk again. This is with Arc++ set to Google TTS and Chromevox using Google TTS. At times, both talk together. In this instance though. Chromevox goes silend when Talkback is talking. This may be fixed when Arc++ voice becomes available in Chromevox, however this is not yet the case.