In Sound, the devices shown are my Logitech speaker and my internal speakers. My speakers are working fine for everything else, but no sound when trying to use Text to Speech. I tried both speakers and no difference. There is something else screwing it up, and I don't know how to tell what it is. Thanks, Joe.
In System Preferences > Sound, check the Input and Output settings to be sure the correct devices are selected and check their volume settings.