SIRI doesn't speak after Tahoe upgrade

I recently upgraded from Sequoia to Tahoe and discovered that SIRI no longer speaks responses. Responses are displayed, and I can navigate to them with VoiceOver. But that's tedious. I'd rather have spoken responses. I've checked and toggled several settings to no effect. Toggling Apple Intelligence on and off, toggling listen to SIRI on and off, toggling type to SIRI on and off, trying SIRI with VoiceOver enabled or disabled, ensuring the SIRI voice is downloaded, testing with other SIRI voices, and toggling between Prefer Spoken Responses and Automatic. But no joy in Mudville. It's not an audio output issue, as VoiceOver, Music, and system sound effects all play loud and clear. A search through Apple Support indicates I'm not the only one with this issue, but I didn't find any satisfactory fixes. If you have experienced the same problem and found a fix for it, please share your remedy. Thanks.