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Web Audio is unavailable in this browser; the plan and exports still work.

Pink and brown are softer starting points; White mask and Blue focus are brighter.
{{ displayVolume }}%
Start low and keep alarms or other important cues clearly audible.
%
Keep this conservative cap on for ordinary use; real output still depends on the device and listening distance.
{{ safe_volume_mode ? 'On' : 'Off' }}
Use 0 for continuous playback or choose a 30–90 minute bedtime window.
min
Use seconds from 0 to 600; both values are included in the wind-down artifact.
Fade in
s
s
{{ stereo_width_percent }}%
Wider settings can feel more spacious; keep 0 for a steady centered bed.
The low cut must remain below the high cut; recipe defaults still define the starting character.
Low cut
Hz
Hz
Use 0 Hz to keep the recipe steady; subtle rates below 0.3 Hz suit slow drift.
Rate
Hz
%
Choose the hum you hear, or leave the notch off.
{{ Number(spectrum_smoothing).toFixed(2) }}
Higher values make the live bars change more gently.
Keep on to avoid surprise background playback after switching tabs.
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Masking works by reducing contrast. A pipe click or distant engine is easier to notice in a nearly silent room than against a steady low-level sound with energy in a similar frequency range. The added sound does not remove the disturbance; it can make mild changes less prominent.

Noise color describes how random sound energy is distributed across frequency. White noise is comparatively bright, pink noise slopes toward lower frequencies, brown noise is weighted more heavily toward low frequencies, and blue noise emphasizes upper frequencies. Comfort depends on the room, playback device, distance, hearing, and the sound being masked, so a color name is only a starting point.

Room soundUseful starting characterReason to adjust
Voices or varied household noisePink broadband soundLower the high cut if the result feels hissy.
Distant traffic or low rumbleBrown-weighted soundRaise the low cut if bass becomes tiring or vibrates nearby surfaces.
Steady fan or ventilation toneFiltered white sound with a 50 or 60 Hz notch if neededUse the notch only when that hum is actually present.
Need for alarms, a child, or another safety cueVery low level or no maskingMasking must not hide sounds that require a response.

Timers and fades shape the session rather than the noise color. A gentle fade can avoid an abrupt start or stop, while continuous playback may be unsuitable when there is no reason for sound to run all night. Slow movement can make a steady bed feel less mechanical, but deep or fast changes can become the new distraction.

A browser volume percentage is not a sound-pressure measurement. Actual exposure depends on speakers or headphones, device gain, distance, fit, and listening duration. Keep the real level low, preserve alarms and other important cues, and stop if the sound causes discomfort, ringing, or difficulty hearing afterward.

How to Use This Tool:

Choose the softest recipe that covers the distracting sound, then test it at a low real listening level.

  1. Choose Sound recipe. Pink drift and brown hush are softer bedtime starting points; white mask is brighter, and blue focus is intended more for wakeful focus than sleep onset.
  2. Set Loudness low and leave Safe-volume mode on for ordinary use. The mode caps the requested relative level at 45%, but it does not measure decibels at your ears.
  3. Choose a Sleep timer from 0 to 120 minutes and fades from 0 to 600 seconds. A timer of 0 means continuous playback.
  4. Adjust the filter only when the room gives you a reason. Raise Low cut to reduce rumble, lower High cut to soften brightness, or select a 50 or 60 Hz Hum notch for matching mains hum.
  5. Press Play, listen from the intended distance, and confirm speech, alarms, and other important signals remain audible. The sound settings lock during active playback.

Interpreting Results:

Effective volume is the requested percentage after the optional 45% cap. It is a relative browser setting, not dBA. The masking spectrum is also a planning score from 0 to 100, not a measured room spectrum or calibrated equalizer response.

Use the coach notes to catch a bright recipe, short fade-out, disabled cap at a high request, or continuous timer. The wind-down chart allocates the selected session among fade-in, steady playback, and fade-out; it does not predict when sleep will begin or whether sleep quality will improve.

Technical Details:

Playback synthesizes a looping stereo noise buffer in the browser. The chosen color changes how each random sample is shaped, stereo width blends shared and independent channel noise, and high-pass, low-pass, and optional notch filters set the audible range. Slow movement can modulate the low-pass frequency when both rate and depth are above zero.

Transformation Core

StageTransformationControl effect
Noise sourceCreate a three-second stereo buffer and loop it.Recipe selects white, pink, brown, or blue sample shaping.
Stereo blendMix a shared random sample with independent left and right samples.0% is centered; 100% uses the widest independent blend.
Filter rangePass the signal through high-pass and low-pass filters.Low cut must be below high cut; accepted bounds are 20 to 1,000 Hz and 500 to 20,000 Hz.
Hum reductionApply a narrow notch when 50 or 60 Hz is selected.Off leaves this reduction inactive.
EnvelopeRamp gain at the start and before a timed stop.Fade durations are limited to the available session time.

Formula Core

The loudness control is converted to gain with a square curve. If V is the effective relative volume percentage, the gain multiplier G is:

G=(V100)2

At an effective setting of 32%, the target gain is 0.1024. With safe-volume mode on, a requested 70% is first capped to 45%, so the target gain becomes 0.2025. This nonlinear control gives more adjustment room at low settings; neither value can be converted to dBA without measuring the complete playback setup.

Band scores begin with seven fixed recipe strengths at 40, 80, 180, 500, 2,000, 6,000, and 12,000 Hz. Filter limits attenuate bands outside the selected range, movement and stereo choices add small recipe-planning adjustments, and effective volume scales the score. Values are rounded and clamped from 0 to 100 for the chart.

A timed session converts minutes to seconds. Fade time is converted to minutes, clipped to the planned duration, and subtracted before calculating the steady interval. Continuous mode uses a 60-minute projection for the chart but schedules no automatic stop.

Safety and Limitations:

Generated sound is not calibrated, does not measure the room, and cannot establish a safe exposure level. The 45% cap is a conservative relative setting only. Headphones can produce very different sound pressure from speakers at the same browser percentage.

  • Do not use masking where it could hide smoke alarms, medical alarms, a child, traffic, machinery, or another warning signal.
  • Persistent tinnitus, muffled hearing, pain, or sound sensitivity warrants a break from audio and professional hearing advice.
  • Masking may make environmental noise less noticeable, but it does not diagnose or treat insomnia, tinnitus, anxiety, or another health condition.
  • No microphone input or audio upload is used; playback is synthesized in the current browser session.

Worked Examples:

Softening intermittent hallway noise

Start with Pink drift at its 32% relative setting, use a 45-minute timer, and keep the 12-second fade-in and 45-second fade-out. Lower the high cut if the sound feels bright, then confirm a phone alarm remains clear from the bed.

Steady electrical hum

Use Fan room and select the 50 or 60 Hz notch that matches the hum in your region or equipment. If neither setting makes a clear improvement, turn the notch off rather than assuming the disturbance is mains hum.

References: