I’ve been using and loving this app for years now. The wide selection of sounds, tones, and frequencies for the user to pick and choose from makes it perfect for customizing for different uses. I have favorites for studying, writing, meditation, and sleeping. The only improvement I would like to see is a mix volume slider. While users are able to set the volume for the individual sounds, tones, and frequencies inside a mix, there’s no capability to turn the whole thing down in proportion beyond the phone’s main volume control. This usually isn’t a problem, however I often like to turn this app on while listening to a lecture or guided meditation, and it can be difficult to get the volume on this app to not intrude on the volume of another. Other than that one nit-picky thing, this app is one of my favorites.