A family of Microsoft word processing software products for creating web, email, and print documents.
I reported the problem to a Microsoft Support technician in an online chat accessed from the Help menu of Word. I was told this was a recognised problem, with a solution. Namely, to reinstall the latest version of Office (Co pilot?) which will be out soon in an automatic update. I had a choice of doing this myself by following instructions or allow him to take over my PC and install the update for me. I chose the latter. It was quick and efficient, but it didn't really work. The voices are marginally better but still haven't returned to the previous fully-natural ones. But I did try!