I am gathering this is not the right app for this! I was really hoping to find a way to sing in harmony with my partner. I don't think there's a way to get even close to a cell phone in terms of sync. And of course, cell phones are notoriously out of sync.

If you have any advice on how my music partners and I can work out harmonies live, that'd be great. Maybe I don't quite understand how this app works, but it seems you're never able to listen to each other in anything close to realtime. I know the big studios do it … but how?

jammr is not real-time. You can use it for practicing the same harmonies over and over again, but it will not allow you to run through a long piece of music or adapt to each other in real-time.

There are real-time jamming systems, try searching online. They require careful hardware/software/network setup to work acceptably. It's not as simple as installing an app and jamming - this is why jammr uses the interval-based jamming approach instead.

Good luck!