This is a straightforward app to help you achieve a chosen mind-state by generating what are known as "binaural beat audio waves" through your headphones, either from your iOS device or your Apple Watch.
Depending on the frequency that you pick, based on the chart included in the app, it can potentially help with sleep, meditation, relaxation, or even for getting a short burst of energy.
I have used similar apps for a while and have found them useful in helping me relax, or helping me float into a creative mood - Except most are overloaded with features that I never use and also cost money, have in-app purchases for "special programmes" and so on.
So I decided to build one that does the same, works offline, has no ads or spying, works well, and is free. There's also an Apple Watch app included which you can use if you're mediating or relaxing away from your phone.
As such, this app just generates the binaural frequency audio hum, and some optional white or brown noise to help mask outside sounds. You can then put it in the background and combine its audio with any other sound generator you like, or play music, radio, and so forth. All it does is to create the useful brainwave frequency, and then it gets out of your way.