Slo: Sleep Sounds, Brown Noise

Slo is a dedicated sound machine app offering over 150 curated sounds for sleep, focus, and relaxation. It centers on deep brown noise, which you can play alone or mix with other sounds like rain, waves, and fans. Each layer in your mix has its own volume control, and a sleep timer automatically stops playback after you drift off.

The app includes a wide range of sound categories: brown, white, pink, and green noise; binaural beats and solfeggio frequencies (396–963 Hz, including 432 Hz and 528 Hz); rain and thunderstorms; ocean waves and water sounds; fan noises like ceiling fan and airplane cabin; and nature ambience such as forest, birds, and campfire. This variety lets you create a personalized soundscape for any situation.

Slo is designed for light sleepers who need to mask disruptive noises, students and deep workers seeking steady background sound, and anyone winding down with binaural beats or frequencies. It's also used by people with tinnitus to make ringing less noticeable. The app focuses on simplicity—no voices or playlists, just consistent sound that sits in the background.

You can download Slo for free and try it out; the full sound library is available as a premium purchase inside the app. Whether you need help falling asleep, studying, or relaxing, Slo provides a customizable audio environment tailored to your needs.