When running, the km pace voice stops my music from playing

Hey there FrustratedJogger,

Thanks for reaching out to the Apple Support Communities.

If wanting to turn off Voice Feedback to prevent Siri from interrupting your music during a workout, you can do this by going into the Apple Watch app on your iPhone or the Settings app on your Apple Watch, tap Workout, then turn Voice Feedback off.

Check out this link here for more details: Start a workout on Apple Watch – Apple Support (UK)

Adjust Apple Watch during a workout

Your Apple Watch can be an active partner even during your workout. While working out you can do the following:

- Check your progress: Raise your wrist to see your workout stats, including your goal completion ring, elapsed time, average pace, distance covered, calories burned, and heart rate. (There’s no goal ring if you haven’t set a goal.) Turn the Digital Crown to see additional Workout Views, which can include Segment, Power, and Elevation. You can also receive voice feedback for key alerts and progress against your Activity rings. To turn Voice Feedback on or off, open the Settings app  on your Apple Watch, tap Workouts, then tap Voice Feedback.

Let us know if that's able to help.

Have a great day!