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How noisy is a small wind turbine, really?
Between 48 and 55 dB(A) at 10 m — quieter than a conversation, but audible at night when the background drops to 25 dB. Distance and blade design decide whether it is a neighbour problem.
The numbers
| Model | @ 10 m | @ 40 m | Comparable to |
|---|---|---|---|
| 300 W | 48 dB(A) | 36 dB(A) | Quiet library |
| 1 kW | 52 dB(A) | 40 dB(A) | Suburban night |
| 3 kW | 54 dB(A) | 42 dB(A) | Quiet conversation |
| 5–10 kW | 55 dB(A) @ 15 m | 43 dB(A) @ 40 m | Refrigerator hum |
Sound falls about 6 dB per doubling of distance. From 10 m to 40 m that is a 12 dB drop — which is why siting, not silencing, solves most noise complaints.
What you actually hear
Two different sounds: a low-frequency 'swish' as each blade passes the tower (about once per revolution, so 3–5 Hz for a small machine), and a broadband aerodynamic hiss from the trailing edge. Geared turbines add a third: a mechanical whine at the gear mesh frequency.
Direct-drive machines have no gearbox, so they eliminate the whine entirely. Blade swish remains, and it is reduced by lower tip speed, a serrated trailing edge and a thicker trailing edge profile — all of which cost a little efficiency.
Distance is the whole answer
Most jurisdictions apply a limit of 45 dB(A) at the nearest dwelling at night, some 40 dB(A). With a 54 dB(A) source at 10 m, you need roughly 40–50 m of separation to meet 45 dB(A), and 70–80 m for 40 dB(A).
Terrain helps: a hedge, a bank or a line of trees between tower and house cuts 3–6 dB(A). So does mounting the turbine downwind of the house relative to the prevailing wind.
When noise becomes a dispute
Complaints almost always come from tonal noise (a whine), low-frequency pulses inside a bedroom, or shadow flicker rather than from the broadband swish. If you are within 100 m of a neighbour, choose a direct-drive machine, keep tip speed below 65 m/s, and offer to log sound levels for the first month.
