Catalina forces ambient noise reduction, and it’s as bad as it sounds.
There is no longer a checkbox in sound preferences to disable ambient noise reduction, which has always made people sound extremely garbled even during everyday conversation. Since so many people use the Mac for recording pro audio and not everyone has an external microphone, this seems like a huge deal. I’ve been googling this for a while and have come up with nothing except complaints and people who claim apple is “aware of the issue”. I’m forced to assume that if Apple has not fixed it since the release of Catalina, they either don’t care or have intentionally chosen to leave it this way in order to insure a good experience in Facetime conferences, etc. And that apparently those experiences are more important than being able to record “pro” audio with my MacBook “pro”. Nobody has commented saying the checkbox is there for them, and nobody I know has the checkbox on Catalina.
In short, “What the hell, Apple?”