Hey there CjmTechie,
Thanks for reaching out to the Apple Support Communities.
To get started, does your wife have a case or film on the iPhone? If so, does the issue persist if you remove the accessories from the device? This may be able to help determine if one of the accessories may be blocking the microphone on the device.
If still having issues after removing any accessories on the iPhone, check out the steps in this next link that can help troubleshoot the issue further: If the microphones on your iPhone aren't working - Apple Support
Lastly, when you set up Siri again, did you or your wife go through the set up? If you set up Siri again using your voice, it can be expected for Siri to not respond to someone else's voice. To resolve this, have your wife go through the set up again so Siri recognizes her voice instead: If "Hey Siri" isn't working on your iPhone - Apple Support
Set up Siri to recognize your voice
1. Go to Settings.
2. Tap Siri & Search.
3. Turn off Listen for "Hey Siri," then turn it back on.
4. When the Set Up "Hey Siri" screen appears, tap Continue.
5. Say each command that you see on your screen.
6. Tap Done.
Let us know if that's able to help.
Take care!