White, pink and brown noise
These are steady sounds that differ mainly in how much of the high end they keep.
- White noise has equal energy across all frequencies. It's a hiss, like an untuned radio. It's the best at covering voices, but many people find it harsh.
- Pink noise turns the high end down. It sounds like steady rain or wind, softer than white noise.
- Brown noise turns it down further. It's a deep rumble, like a waterfall or the inside of a plane, and the one people most often find calming.
Nature and café sounds
Rain, wind, a crackling fire or a busy café have more variety than plain noise, which some people find nicer over a long session. Café sound is popular for writing: a murmur of voices you can't make out can feel like working alongside other people.
Why lyrics get in the way
Words compete with words. If you're reading or writing, songs with lyrics in a language you understand tend to pull at your attention. Instrumental music and lofi are safer, and music you know well is less distracting than something new.
Binaural beats
Binaural beats play a slightly different tone in each ear, which you hear as a slow pulse. Some people like them for focus, but the research is limited and mixed, so treat them as one more thing to try. They only work with headphones.
Use sound as a cue
The most reliable benefit isn't the sound itself, it's the habit. Play the same sound whenever you start a focus session and stop it on breaks. After a week or two, starting the sound helps you start the work.
ZenTab does this for you: ambience starts with your focus timer, goes quiet for breaks, and keeps playing with the popup closed. Rain, brown noise and café are free; Pro adds all 12 sounds, a mixer, binaural beats and your own songs.
Keep the volume low
Sound should stay in the background. If you keep noticing it, it's probably too loud, and a lower volume also protects your hearing over long days in headphones.