In iOS 9.3, head to Settings > General > Accessibility. Both iOS and Android let you adjust the audio volume balance between the left and right channels as well as enable mono audio to ensure no sounds get lost in the process. Instead of playing audio to both sides of her headphones, we set it up so that all audio is redirected to her left ear. But she uses them a bit differently than most. On long road trips or while she's in the same room with her little brother, she uses headphones. My daughter, who is deaf in one ear, likes to watch movies and listen to music on her iPad.
