The short answer: a HNordic WindWhisperer vertical axis wind turbine produces 35 dB @ 3 m — quieter than a normal conversation, and well within residential noise limits in the UK, Sweden, and Scandinavia.
But the decibel figure alone does not tell the full story. The character of the sound matters as much as its level.
If you have ever lived or worked near a large wind farm, you will be familiar with the sound. It is not a steady background noise. It is a rhythmic, pulsing swoosh — a slow "whumph, whumph, whumph" that repeats with every blade rotation. This effect is called amplitude modulation, and it is one of the most persistent complaints associated with conventional horizontal-axis wind turbines (HAWTs).
Amplitude modulation happens because the long blades of a large HAWT pass through a zone of disturbed air near the tower on every rotation. As the blade tip — travelling at speeds of 70 metres per second or more — cuts through that turbulence, it generates an aerodynamic pulse. The sound level rises and falls with each pass, creating the characteristic rhythmic swoosh that carries across long distances and is particularly disturbing indoors at night.
On top of that, the rotating blades cast moving shadows across the ground and nearby buildings — a phenomenon known as shadow flicker. At certain times of day and year, those rotating shadows can sweep through windows repeatedly, which is distracting and, for some people, physically uncomfortable. Shadow flicker is a material planning consideration in the UK and many other jurisdictions, and it can determine whether a conventional turbine receives planning permission at all.
The UK government's reference document for wind turbine noise assessment, ETSU-R-97, sets out how amplitude modulation is assessed and why it can trigger additional noise conditions even when average dB levels appear acceptable. It is a genuine, well-documented problem — not a perception issue.
A vertical axis wind turbine works on a different mechanical principle. The rotor spins around a vertical axis, and the blades move continuously around the full circumference. There is no single point where a blade passes close to a mast or tower structure. There is no rhythmic pulse.
The sound a VAWT produces is a smooth, steady hum — the result of aerodynamic flow across the blade surfaces at moderate, consistent speed. It is closer in character to the background hum of ventilation equipment than to the intrusive swoosh of a large HAWT.
The HNordic WindWhisperer rotates at a maximum of 0–550 RPM with a rotor diameter of 1.6 m. Blade tip speeds are a fraction of those on large horizontal-axis machines. At those speeds, there is no amplitude modulation effect and no shadow flicker.
The WindWhisperer 100 Max measures 35 dB @ 3 m at 3 metres from the turbine. To put that in context:
| Sound source | Typical level |
|---|---|
| Quiet library | ~30 dB(A) |
| Quiet bedroom at night | ~35 dB(A) |
| Normal conversation | ~60 dB(A) |
| Conventional small wind turbine | ~45–55 dB(A) at 3 m |
The World Health Organization's Environmental Noise Guidelines for the European Region (2018) recommends that wind turbine noise should not exceed 45 dB(A) Lden outdoors at dwellings. The WindWhisperer operates well below that threshold even at very close range.
In Sweden, Naturvårdsverket (the Swedish Environmental Protection Agency) publishes guidance on wind turbine noise recommending outdoor noise levels at dwellings not exceed 40 dB(A). In the UK, ETSU-R-97 sets indicative limits typically in the range of 35–40 dB(A) at the nearest noise-sensitive receptor, with lower limits applying at night.
At 35 dB @ 3 m, a WindWhisperer turbine installed at typical setback distances from occupied buildings falls within these limits in all three markets.
Because the WindWhisperer rotor is compact (1.6 m diameter, 4.4 m tall) and spins on a vertical axis, the blade geometry does not produce the sweeping shadow patterns that affect planning assessments for large HAWTs. UK planning guidance (Planning Practice Guidance on renewable energy) identifies shadow flicker as a consideration for horizontal-axis turbines with rotor diameters above a threshold relevant to large machines. It is not a factor for compact VAWTs.
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