2026 study Senses: Sound

The turbines at 2 am

A developer needs to know which homes will exceed the noise limit and which turbines will have to run quiet at night, before the layout is frozen. The public record shows what that costs: at Crowned Ridge, South Dakota, the PUC had 16 of 87 turbines shut above 6 m/s hub wind until quieter blades were fitted.

Non-participating homes over 45 dBAlimit 45 dBA, PUC Condition 26--

Participating homes over 50 dBAlimit 50 dBA--

Home nearest its limit----

Turbines shut now----

Planner clears every home with----

Hub wind--

None shut Filing's 16 Planner's 7

Check against the filing

Assumptions

From the filings: 87 GE 2.3-116 at the Table A1 coordinates, 9 on 80 m towers and the rest on 90 m; 8 with low-noise trailing edges in winter 2019-20; 107.5 dBA standard and 106 dBA LNTE plus EAPC's 2 dBA margin; G 0.3 per the waiver order; receivers 1.5 m up; 137 occupied structures with participation status (EAPC Table A4).
Assumed: no GE 2.3-116 octave spectrum is public, so its bands take the V163-4.5 STE shape from the Homestead Wind report, scaled to the GE total.
Assumed: below full power the level follows the Nordex N163 curve by wind speed (Carrow EIAR Table 12-4-1); GE's curve is confidential. Flat ground; no Crowned Ridge II turbines.
Your site: V163-4.5 at 108.3 dBA (Homestead Table 4), N163/5.X modes as the stand-in for V163 modes, Wisconsin's 45 dBA night limit, G 0.5 and 4 m receivers as in that report.
Playback is relative, not calibrated. This is not a noise study or a compliance result.

Method and context

Each octave from 31.5 Hz to 8 kHz runs ISO 9613-2: divergence over the slant distance, air absorption at 10 C and 70 percent, and the general ground method with one G. Bands are A-weighted and summed by energy. Python computes every turbine's level at every home and the contour sets; the browser switches turbines off, shifts by the hub wind and sums. The planner stops the turbine loudest at the home furthest over its limit until every home meets it.

Loading Crowned Ridge

Sound power by octave at the hub, and what reaches --

unweighted A-weighted A-weighting's cut received, dBA

Level against distance

one turbine limits the home

Under 35 dBA35 to 40 dBA40 dBA to the limit Over the home's limit Ringed: non-participating Plain: participating Turbine running Turbine shut 45 dBA contour 40 dBA contour