This is a very subjective thing, so it's hard to objectively quantify or "prove", but it feels like the latest Steam Audio beta update (Build 1693) has significantly downgraded the voice quality. I restarted for the update and it feels like night and day.
More specifically, it sounds like the bitrate of voice audio has been cut in half. The only other way I can reproduce the effects of this update is by opening any voip application like Teamspeak, and lowering the bitrate to about 16kbps.
Again, this is a subjective thing so it's very hard for me to say if this is a bug or just a personal subjective effect, but voice quality has gone down a lot in my experience, so I'm making this post as a feedback post.