Hey Lisaraa,
Thanks for using Apple Support Communities! I understand you're not hearing any sound when using multiple navigation apps. I definitely understand how important it is to have sound with your maps/directions, and I'm happy to help.
To start, when using the built in Maps app, after starting navigation from your iPhone, make sure you swipe up and ensure that "No Voice" isn't enabled. You can see how to do that here: Use Maps with a Bluetooth accessory on your iPhone and iPad
You'll also find some helpful information in the resource above under "Allow Navigation Voice Prompts" you may need to connect with your vehicle manufacturer.
You'll find some additional helpful tips for using CarPlay here: Use CarPlay with your iPhone
Thanks again, and have a great day!