White, pink, brown, and blue noise. Live in your browser.

Yes, with the volume cap and distance guidance. Pediatric studies (notably Spencer 1990 and Hugh-Hazelden et al. 2014) found that white noise at safe volume helps newborns settle and sleep longer without measurable hearing-development effects. The key constraints: ≤ 50 dB SPL at the crib (the green zone on most baby monitors), the machine at least 7 feet from the crib, and run for the sleep period rather than continuously through the night.

Pink is more pleasant for most adults and matches the in-utero sound profile that's evidence-based for newborns. White is the broadest masking option but can feel 'hissy' to some ears, especially over hours. The research on slow-wave consolidation (Papalambros et al. 2017) used pink, not white. The recommendation engine on this page picks pink for baby and adult use, brown for office focus.

Because adults often want it. The 8-hour option exists for adult sleep where continuous masking is the user need (e.g., living next to a busy road, partner who snores). For infant use, the form recommends 60 minutes or shorter and warns if you pick the longer option. The medical guidance is age-dependent — adults are not subject to the same continuous-exposure concerns as infants.

Two reasons. One, hosting audio files brings licensing complexity that we haven't worked through — most royalty-free libraries have terms that don't cleanly support unlimited browser playback. Two, generated noise is mathematically pure — no compression artifacts, no loops to fatigue on. Adding the named sounds is on the roadmap once we have a clean licensing path.

Yes. iOS Safari and Chrome both support Web Audio. The one quirk: iOS requires the audio to start from a user gesture (the play button satisfies that). Background playback works on most devices but may be limited by mobile-OS power policies — the timer is a hard backstop in case the OS doesn't suspend the page.

Once the page loads, yes — the audio is generated in your browser, no server calls during playback. The page itself needs to be loaded online first. We're considering a PWA (Progressive Web App) build for full offline support, but it's not on the immediate roadmap.