https://ipadpilotnews.com/2017/12/never-miss-altitude-assignment-altitudealert-app/
https://ipadpilotnews.com/2017/01/using-ipad-audio-make-flying-safer-2/
If you have a headset that offers Bluetooth audio compatibility, like the updated Bose A20, all Lightspeed headsets, the AKG AV100 or the David Clark Pro-X, you can wirelessly connect it to your iPad. Passengers love this feature for music, but it’s valuable for pilots too.
FlightLink is the free, proprietary app that adds enhanced functionality to all Lightspeed headsets