What is grey noise?
Grey noise (also spelled gray noise) is white noise that has been reshaped by an equal-loudness curve, so that every frequency sounds equally loud to a typical listener. White noise has equal energy at every frequency, but our ears are not equally sensitive: we are most sensitive between about 2,000 and 5,000 Hz, the range of consonants and a baby’s cry, and much less sensitive to deep bass and the very top end.
So grey noise turns down the region the ear is most sensitive to and turns up the lows and the highest highs. The result has a clear, “scooped” quality, with more bass than white noise and none of its piercing upper-mid hiss.
How this grey noise is made
The ear’s sensitivity is described by equal-loudness contours, standardized internationally as ISO 226. True grey noise follows the inverse of one of those curves exactly, and the curve changes with listening level. We use a close, smooth approximation of the inverse of the 40-phon contour, roughly the loudness of a quiet room: a lift of the low frequencies below about 200 Hz, a dip centered around 3,500 Hz and a small lift above 11,000 Hz. You can see that U-shape in the spectrum display above.
Grey noise and tinnitus
Grey noise is often suggested for tinnitus because it covers the whole range without any harsh region, so it can sit comfortably around the ringing rather than fighting it. Sound therapy for tinnitus generally aims to make the tinnitus less noticeable, not to drown it out, so a level just below the tinnitus is usually recommended.
If your tinnitus has a clear pitch, the tinnitus sound therapy page lets you find it with a test tone and remove that band from the noise, a technique called notched sound. Anyone with new, one-sided or pulsing tinnitus should see a doctor first.
Grey noise compared with other colors
| Color | Shaped by | Character |
|---|---|---|
| White | Equal energy per frequency | Bright, hissy |
| Pink | Equal energy per octave | Balanced, rain-like |
| Grey | Equal perceived loudness | Even, slightly scooped mids |
| Brown | Energy falling 6 dB per octave | Deep rumble |
Frequently asked questions
Is it grey noise or gray noise?
Both spellings are correct and mean the same thing. Grey is more common in British English and gray in American English.
Is grey noise good for tinnitus?
Many people with tinnitus find it comfortable because no frequency stands out. Keep it at or just below the level of your tinnitus. It is a comfort measure, not a cure, so talk to a doctor or audiologist about ongoing tinnitus.
Why does grey noise sound different to different people?
It is built on an average listener’s hearing. If your hearing differs from that average, for example with high-frequency hearing loss, the balance will sound different to you. Use the Tone slider to adjust it.