Hi dave_a,
Thank you for posting in the Apple Support Communities. I understand the voice used for Siri and spoken content do not match. It sounds like you'll need to adjust your speech settings.
"Change the speech settings
- Go to Settings > Accessibility > Spoken Content.
- Adjust any of the following:
- Speak Selection: To hear text you selected, tap the Speak button.
- Speak Screen: To hear the entire screen, swipe down with two fingers from the top of the screen.
- Speech Controller: Show the controller for quick access to Speak Screen and Speak on Touch.
- Highlight Content: iPhone can highlight words, sentences, or both as they’re spoken. You can change the highlight color and style.
- Typing Feedback: You can configure typing feedback for the onscreen and external keyboards and choose to have iPhone speak each character, entire words, auto-corrections, auto-capitalizations, and typing predictions.
- To hear typing predictions, you also need to go to Settings > General > Keyboards, then turn on Predictive.
- Voices: Choose a voice and dialect.
- Speaking Rate: Drag the slider.
- Pronunciations: Dictate or spell out how you want certain phrases to be spoken."
You'll find more information regarding speech settings linked below.
* Hear iPhone speak the screen, selected text, and typing feedback
Cheers!