"Infrasound" is the part of the acoustic spectrum below 20 Hz - below what most humans consciously hear. It is produced by trucks, coastal waves, ventilation shafts and wind turbines. The question is not whether turbines emit it (they do) but whether the levels they emit at residential distances are large enough to harm sleep or well-being.
What we can measure
Modern 3 MW turbines produce infrasound peaks in the 1-5 Hz band that are measurable up to 2-3 km from the mast. At 500 m the unweighted sound pressure level is typically in the 70-80 dB(Lin) range, dropping to the low 60s at 1,500 m. Those values are comfortably below the 150 dB threshold for tissue damage, but well above what cochlear inner hair cells can respond to.
Where the science disagrees
The ANSES 2017 report concluded that current evidence does not support a direct physiological harm from turbine infrasound at residential distances. The WHO 2018 guidelines reached a similar verdict for audible noise but explicitly did not rule on infrasound due to insufficient data.
Independent reviews (Schmidt & Klokker 2014) found a clear, dose-dependent relationship between audible noise and sleep disturbance, but only a weak and inconsistent link with infrasound. Some authors (Jeffery 2013) argue the studies dismissing infrasound were underpowered and relied on self-reported sleep data.
"We lack the long-term cohort studies that would settle the question. Until we have them, a precautionary setback is a reasonable policy."
How ClearSpot treats it
Because infrasound sensitivity is highly individual, our wind module exposes two thresholds:
- Legal verdict (500 m) - the current French law.
- Precautionary verdict (1,500 m) - the distance at which most reviewed studies see self-reported symptoms fall to background.
If you opted in to the "wind" sensitivity during onboarding, the precautionary verdict is what drives the red "NOT CLEAR" chip on the home page.