HzLab: Solfeggio & Noise

Plenty of apps will play you a “healing” frequency.
This one plays the same tones — but it always shows you how far the research on that frequency has actually got, right next to the play button.

■ Start from a goal, not a number
Sleep / Relaxation & Anxiety / Focus & Cognition / 40 Hz Gamma Stimulation / Pain Self-Care / Solfeggio & 432 Hz / Noise.
Follow one of seven categories and you arrive at the tone you came for. No knowledge of hertz required.

■ Every tone carries its evidence rating
All 38 items are labeled with a four-level rating of the human research behind them.

• Moderate — several human studies or a meta-analysis
• Low–moderate — clear in physiological measures, unproven clinically
• Low — small, exploratory, or conflicting results
• No evidence — no controlled study supports an effect specific to that frequency

The player screen gives you the study year, the sample size, the conditions, and the negative findings too.
It says plainly that the claim “1 Hz gives you deep sleep” is not supported, and that the study usually cited for 528 Hz had about nine participants.

■ The popular frequencies are here — honestly
432 Hz, 528 Hz, and the full 174–963 Hz Solfeggio set are all playable. They are simply labeled with the fact that no human clinical evidence supports claims like “resonates with the universe” or “repairs DNA.”
We think putting the fact next to the claim is more useful than deleting the claim.

■ What's inside (38 items)
• Sleep: binaural beats at 0.25 / 1 / 3 / 6 Hz, plus white, pink, and brown noise
• Relaxation & Anxiety: theta binaural, 6 / 10 Hz monaural beats, 40 Hz isochronic
• Focus & Cognition: white and pink noise, binaural beats at 10 / 16 / 25 / 40 Hz
• 40 Hz Gamma: amplitude-modulated tone, isochronic, monaural, 60 Hz
• Pain Self-Care: alpha entrainment, 40 Hz, theta binaural
• Solfeggio & 432 Hz: 432 and 528 Hz plus the complete 174–963 Hz set
• Noise: white, pink, brown

■ Synthesized on your device
Nothing here is an audio file. Each waveform is computed sample by sample as it plays, so there is no loop seam and no compression artifact, however long you leave it running.
Supports pure tones, binaural beats, monaural beats, isochronic tones, amplitude modulation, and three noise colors.

■ Custom frequency generator
Pick a method, then dial the carrier from 20 to 1000 Hz and the beat from 0.25 to 60 Hz, with presets at 40, 100, 250, 432, and 528 Hz.

■ Night mode, for bedtime
Beyond System, Light, and Dark, a Night mode takes the screen almost to black, with the dimming on a slider.
The sleep timer runs 15, 30, 60, or 90 minutes, and background audio keeps playing with the screen off.

■ Seven languages
Japanese, English, Simplified Chinese, Korean, Spanish, French, and German — including every research note.

■ Nothing collected, nothing sent
• No account, no sign-in
• No analytics, no tracking
• No access to the microphone, camera, location, or health data
• No connection needed at all — every feature wo