Somni - sleep comes easily 12+

Somni lets you play audio in one ear and masking sounds in the other.
Audio and sounds can be swapped left to right and each has it's own independent volume control.
Somni has two audio books and six fairy tales and you can load local MP3s from the files app. These could be podcasts, music or audio book chapters.
You can record your own songs and stories using the built-in Voice Memos app and open these in Somni. Mum's and Dad's can save their child's bedtime stories and songs and open them in the app.
Somni aims to help you to get to sleep easily. The concept is to become familiar with the book so you do not need to know what's coming next. The chapters become old friends and listening to the narrative helps you drift off to sleep quickly.
Chapters play continuously until the book ends.
If you need white noise to mask Tinnitus then you can choose one of the masking tracks built in to the app. There are also two musical tracks.
The design is minimalist and supports dark mode. At it's simplest you just set the volumes left and right and touch 'play'.
You can choose chapters and move through the current chapter using a slider. The app remembers your current position if you touch 'stop' and exit from the app.
The app plays audio and sounds in the background.
There is a one hour sleep timer which helps save battery life. Audio controls appear on the lock screen and on your Apple watch.