Hi Paul4100,
We appreciate you coming out to Apple Support Communities for help with your wife's new iPhone SE. We're happy to help ensure her awesome new iPhone is working as expected when using the speakerphone in calls.
To start, let's ensure we're on the same page. Has your wife had an opportunity to restart her device since noticing this?
If so, let us know the exact version of iOS installed. This can be found under Settings > General > About.
If an update is available, we recommend backing up and updating your iPhone following the steps in this guide:
Update your iPhone, iPad, or iPod touch
Additionally, go through all of the troubleshooting listed here:
If you hear no sound or distorted sound from your iPhone, iPad, or iPod touch speaker
We're here for you if you've got any questions.
Have a great day!