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Resource Documents: Noise (670 items)


Also see NWW press release on noise

Unless indicated otherwise, documents presented here are not the product of nor are they necessarily endorsed by National Wind Watch. These resource documents are shared here to assist anyone wishing to research the issue of industrial wind power and the impacts of its development. The information should be evaluated by each reader to come to their own conclusions about the many areas of debate. • The copyrights reside with the sources indicated. As part of its noncommercial effort to present the environmental, social, scientific, and economic issues of large-scale wind power development to a global audience seeking such information, National Wind Watch endeavors to observe “fair use” as provided for in section 107 of U.S. Copyright Law and similar “fair dealing” provisions of the copyright laws of other nations.

Date added:  March 3, 2020
Australia, NoisePrint storyE-mail story

Prevalence of wind farm amplitude modulation at long-range residential locations

Author:  Hansen, Kristy; Nguyen, Phuc; Zajamšek, Branko; Catcheside, Peter; and Hansen, Colin

ABSTRACT – The presence of amplitude modulation (AM) in wind farm noise has been shown to result in increased annoyance. Therefore, it is important to determine how often this characteristic is present at residential locations near a wind farm. This study investigates the prevalence and characteristics of wind farm AM at 9 different residences located near a South Australian wind farm that has been the subject of complaints from local residents. It is shown that an audible indoor low-frequency tone was amplitude modulated at the blade-pass frequency for 20% of the time up to a distance of 2.4 km. The audible AM occurred for a similar percentage of time between wind farm percentage power capacities of 40 and 85%, indicating that it is important that AM analysis is not restricted to high power output conditions only. Although the number of AM events is shown to reduce with distance, audible indoor AM still occurred for 16% of the time at a distance of 3.5 km. At distances of 7.6 and 8.8 km, audible AM was only detected on one occasion. At night-time, audible AM occurred indoors at residences located as far as 3.5 km from the wind farm for up to 22% of the time.

Kristy L. Hansen, Phuc Nguyen, College of Science and Engineering, Flinders University, Tonsley, Australia
Branko Zajamšek, Peter Catcheside, College of Medicine, Flinders University, Bedford Park, Australia
Colin H. Hansen, School of Mechanical Engineering, University of Adelaide, Australia

Journal of Sound and Vibration 455 (2019) 136–149. doi: 10.1016/j.jsv.2019.05.008

Download original document: “Prevalence of wind farm amplitude modulation at long-range residential locations

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Date added:  February 14, 2020
Minnesota, Noise, Regulations, TechnologyPrint storyE-mail story

Why “Ground Factor” Matters

Author:  Overland, Carol

Minn. R. 7030.0400 is the MPCA’s noise rule, setting standards for industrial noise. It was developed to limit industrial noise, from a noise source on the ground to a “receptor” on the ground. ISO 9613-2 was also developed to measure ground based noise reaching a ground based receptor.

A primary input is the “ground factor” set to address conditions on the ground, the ground effect, between the noise source and the receptor:

7.3  Ground effect (Agr)

7.3.1  General method of calculation

Ground attenuation, Agr, is mainly the result of sound reflected by the ground surface interfering with the sound propagating directly from source to receiver.

While there may be some reflected sound reaching the “receptor” (that is such an obnoxious term for people!), the sound from a wind turbine with a hub height of 300 feet or more! That’s a direct path to the “receptor.” The ground, grasses, corn, trees, buildings, do not get in the way.

The ground factor to be used for wind turbines is ZERO.

Dr. Schomer stated this clearly and thoroughly in the Highland Wind docket in Wisconsin (PSC Docket 2535-CE-100).

Download  Schomer Pages from Transcript Vol 4 (see page 572)

The use of a 0.0 ground factor for wind is standard practice, and that a 0.5 ground factor is NOT appropriate for wind because it’s elevated. This was inadvertently confirmed by Applicant’s Mike Hankard in the Badger Hollow solar docket, also in Wisconsin (PSC Docket 9697-CE-100):

The model that we use has been shown to predict conservatively with 0.5. I mean, 0.5 ground factor is used in probably – well, with the exceptiion perhaps of wind turbine projects which are different because the source is elevated. But for projects like a typical power plant, a solar plant where the sources are relatively close the ground, I would say 90 to 99 percent of the studies use 0.5. And when consultants like myself go out ad measure these plants after they’re cpmnstricted tp verify our modeling assumptions, that assumption checks out as being, if anything, overpredicting the levels. So there’s no need to – there would be no justification to use something like a .2 or .3 which would predict yet higher levels because we’re already demonstrating that the model is probably overpredicting. So that would not be justified for those reasons.

Who cares? Well, it’s bad enough that in that WI PSC Highland Wind docket, when the applicants couldn’t comply with the state’s wind noise limit, they redid their noise “study” using the inappropriate ground factor of 0.5 to give them more compliant numbers – they moved the goal posts, garbage in, garbage out. They think they can do that in Minnesota too, and are trying oh so hard in the Freeborn Wind docket (PUC Docket 17-410).

Last September, 2018 that is, Freeborn Wind did a deal with Commerce, admitted to in its “Request for Clarification/Reconsideration” pleading:

Freeborn Wind requests the Commission clarify its Site Permit to adopt Section 7.4, as proposed by Freeborn Wind and agreed to by the Department and MPCA, in place of the current Sections 7.4.1 and 7.4.2, to both ensure consistency with the Order and avoid ambiguity in permit compliance.

Freeborn Wind’s September 19, 2018, Late-Filed proposal for Special Conditions Related to Noise outlines the agreement reached between Freeborn Wind, the Department and the MPCA on this issue.

(fn. citing Late Filed—Proposed Special Conditions Related to Noise (Sept. 19, 2018), eDocket No. 20189-146486-01).

In this deal, they put language in the permit that was a fundamental shift in noise monitoring, one for which there is no justification under the noise modeling standards, whether state or ISO 9613-2 – that of using a 0.5 ground factor.

The language in the proposed special conditions requires Freeborn Wind to submit updated modeling and/or proposed mitigation demonstrating that modeled wind turbine–only noise will not exceed 47 db(A) L50-one hour at receptors. Specific guidance is included regarding the modeling assumptioins to be used. Specifically, proposed Section 6.1 directs Freeborn Wind to follow the NARUC ISO 9613-2 standard with a 0.5 assumed ground factor. As reflected in the special condition language, setting a turbine-only noise limit at 47 dB(A), using the specified model assumptioins, ensures that the Project will not cause or significantly contribute to an exceedance of the MPCA Noise Standards. This limit is supported in this record by expert testimony from Mr. Mike Hankard and the MPCA’s 2015 Noise Guide, both stating the 3 dB(A) is the generally recognized minimum detectable change in environmental noise levels. To illustrate, when nighttime background sound levels are at 50 db(A) L50-one hour, a maximum turbine-only contribution of 47 db(A) L50-one hour would result in a non-significant increase in total sound of less the 3 dB(A).

The day before the Commission’s meeting, they filed for a “Special Condition,” and oh, was it special:

Download  20189-146486-01_LateFiling

At the meeting, they presented a chart with made up numbers on it, not supported by any noise study:

This chart was shown for a few seconds at most, it was not provided in the “Late Filing” above, and there were no copies for parties or the public. Did Commissioners get a copy? Who knows …

The Commission then granted the site permit! There were a few rounds before we got to where we are today, with Xcel Energy acquiring the project, and with a new site plan, bigger turbines, and some specific site permit amendments. In its permit amendment application, Xcel Energy is now the owner of Freeborn Wind, and Xcel wants to use larger Vestas V120 turbines rather than the V116.

From testimony in the original Freeborn Wind hearing, and in an Affidavit submitted by Commerce-EERA’s Davis:

7.  It is generally understood that turbine noise output increases with higher blade tip speeds …
(Aff. of Davis, EERA Motion, 20181-139379-01)

In its permit amendment application, Xcel Energy is now the owner of Freeborn Wind, and Xcel wants to use larger turbines. In so doing, they have filed a noise study, Attachment E, utilizing that 0.5 ground factor. Xcel’s claim is that they’re using a 0.5 ground factor because the permit specifies that:

This Xcel filing is the first noise study in the Freeborn Wind record to utilize a 0.5 ground factor.

This Xcel filing is the first noise study in the Freeborn Wind record following the ALJ’s recommendation of denial:

The Administrative Law Judge concludes that Freebron Wind has failed to demonstrate that the proposed Project will meet the requirements of Minn. R. 7030.0040, the applicable Minnesota Noise Standards. Therefore, the Administrative Law Judge respectfully recommends that the Commission either deny Freeborn Wind’s Application for a Site Permit, or in the alternative, provide Freeborn Wind with a period of time to submit a plan demonstrating how it will comply with Minnesotat’s Noise Standards at all times throughout the footprint of the Freeborn Wind Project.

There’s a 3 dB(A) margin of error – even using Hankard’s numbers, look at the yellow lines right up against the homes, and look at the blue 50 dB(A) lines and how many homes are inside of those lines:

Turbine noise at the hub for the V120s can be maximum of 110.5 dB(A), and serrated edges provide an option to reduce noise (which Xcel says it plans on using for some turbines), per the Vestas spec sheet.

Compliance? Modeling with the improper 0.5 ground factor doesn’t come close to demonstrating compliance, instead it demonstrates a high probability of non-compliance. It demonstrates that using the proper ground factor for wind, it won’t do the modeling, likely (assuredly) because the project cannot comply. Freeborn Wind could not demonstrate that it could comply with state noise standards as originally designed with the smaller wind turbines and the proper modeling ground factor, and now Xcel Energy wants to use larger turbines. Larger turbines are noisier … once more with feeling:

7.  It is generally understood that turbine noise output increases with higher blade tip speeds …

And now we see, hot off the press, the Plum Creek wind project (PUC Docket WS-18-700), proposed by Geronimo …

Vestas 150 and 162 turbines, 5.6 MW each! The noise for the V150 is a maximum of 104.9 dB(A), and for the V162 is a maximum of 104.9 dB(A), with “sound optimized modes available.” That’s in the brochure.

They have provided a noise study, BUT, much is NOT PUBLIC:

201911-157475-05_Noise_Appendix B

And I wonder why … well, it says that they’re not using a ground factor of 0.0. Look at p. 48 of the sound study above, deep breathe and take a peek:

They’re using a ground factor of 0.7 !

Really …

For this analysis, we utilized a ground factor of G=0.7, which is appropriate for comparing modeled results to the L50 levels.18 A 2-dB uncertainty factor was added to the turbine sound power per typical manufacturer warranty confidence interval specifications.

18 Generally accepted wind turbine modeling procedure calls for a ground absorption factor of G=0.5, with a 2-dB uncertainty factor added to the manufacturer’s guaranteed levels, to predict a maximum LEQ(1-hr). In this case the state limit utilizes and L50 metric instead of maximum LEQ(1-hr), which means a ground factor of G=0.7 can be used.


They say it again on p. 62, elsewhere too:

How stupid do they think we are?

How stupid do they think Commerce-EERA is? … oh … never mind …

Anyway, here are the sound study maps based on that bogus 0.7 ground factor – look how many homes are affected:

Geronimo gets the gong:

The applicants know exactly what they’re doing.

At least twice in the Freeborn record I have asked whether the Commissioners understand “0.5 ground factor” and “0.0 ground factor” and have been vigorously assured that yes, they do understand. And Commerce-EERA staff? You’re responsible for doing the footwork on these siting applications. Do you understand?

If they do not understand, or misunderstand, they’ve got some learnin’ and edumacation to do. If they DO understand, and are approving site permits knowing that the modeling is off, that ground factor is misused, they’re complicit. They’re knowingly afflicting those who have to live with the noise sound levels that exceed Minnesota state standards.

As we saw in Bent Tree, where the noise standard compliance is in question, it is Commerce’s job to do the noise monitoring and deal with the problem. Once a turbine is up, there aren’t many options other than “shut down the turbines” or “buy out the landowners.” How many landowner buy-outs do you think we need before it’s admitted there’s a problem? Why is it so hard to develop responsible, precautionary, and respectful siting? Why is there resistance? The costs of their failure to do so are … well … we may see exactly what those costs are.

Commissioners and Commerce staff, make sure you know how the state noise standard and ISO 9613-2 was designed, how it is to be used, and what ground factor means.

If you know what it means, and are siting turbines using 0.5 and 0.7, you are responsible.

Legalectric, November 17th, 2019

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Date added:  January 19, 2020
Health, NoisePrint storyE-mail story

Santé des hommes et des animaux face aux infrasons produits par les éoliennes

Author:  Various

Actes du Colloque du 16 Novembre 2018—

John Yelland, physicien et ingénieur
Jean-Paul Borsotti, neurologue
Marie-Stella Duchiron, Docteur en sciences forestières, ingénieur du génie rural, des eaux et des forêts
Bruno Frachet, oto-rhino-laryngologiste
Gilbert Mouthon, vétérinaire,
Yves Couasnet, Docteur en sciences et techniques du bâtiment (ENCP), ingénieur acousticien
Mariana Alves-Pereira, ingénieur biomédical et docteur en sciences de l’environnement
Henri Delolme, médecin épidémiologiste

Les effets du bruit au travail sur la santé
Le principe de dose-effet en acoustique
Les échelles de bruit
La sonie, unite subjective de psycho-acoustique
Contenu temporel et spectral du bruit d’une centrale eolienne
Les infrasons au coeur d’une vieille controverse
Seuils de sensibilite aux infrasons
Etude en double aveugle et effet nocebo
Etude infrasons à Cape Bridgewater
Propagation des infrasons : Deux regles

Download original document: “La santé des hommes et des animaux face aux infrasons produits par les éoliennes

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Date added:  November 12, 2019
Michigan, Noise, Ordinances, SitingPrint storyE-mail story

Wind Energy Conversion Systems Zoning Ordinance

Author:  Monitor Township, Bay County, Mich.

Section 3.48 [excerpts]

This Ordinance is intended to protect the health, safety and welfare of the residents of the Township and to encourage the safe, effective, efficient and orderly development and operation of wind energy resources in the Township while preserving and protecting the character and the stability of residential, agricultural, recreational, commercial, industrial and other areas within the Township.

Adverse Sound Character: Sound that causes building rattle, is impulsive, tonal, or has low-frequency bass rumble.

Ambient is defined as the sound pressure level exceeded 90% of the time over a 96-hour measurement period with daytime/nighttime division.

Lmax (LAmax or LCmax): The maximum dB(A) or dB(C) sound level measured using the “fast response” setting of the sound meter (equivalent to 0.125 second exponential averaging time).

L10 is the noise level exceeded for 10% of the time of the measurement duration. This is often used to give an indication of the upper limit of fluctuating noise, such as that from road traffic.

L90 is the noise level exceeded for 90% of the time of the measurement duration and is commonly used to determine ambient or background noise level.

Utility-Scale (also known as Commercial and Large-Scale) Wind Energy Conversion System: A wind energy conversion system greater than sixty (60) feet in total height (tip height) intended to generate power from wind primarily to supplement the greater electric utility grid. Utility-Scale WECS includes accessory uses such as, but not limited to, SCADA towers, anemometers, or electric substations.

Review Standards for Commercial Wind Energy Conversion Systems (WECS).

Height and Scenic Vista. The maximum height of any Utility-Scale WECS is 500 feet. The height of a WECS is measured from the lowest natural grade at the base of the pole to the highest point of the WECS when a blade is in its vertical orientation.

Abandonment. Any WECS that is not used to produce energy for a period of six (6) successive months or longer shall be deemed to be abandoned and shall be promptly dismantled and removed from the property in accordance with the decommissioning regulations of this ordinance, unless the applicant receives a written extension of that period from the Township Board in a case involving an extended repair schedule for good cause.

Vibrations. Wind turbines shall not create vibrations that are detectable by humans on non-participating properties.

Safety Manual. The Applicant must provide an unredacted copy of the manufacturer’s safety manual for each model of turbine without distribution restraints to be kept at the Township Hall and other locations deemed necessary by Planning Commission or local first responders. The Manual should include standard details for an industrial site such as materials, chemicals, fire, access, safe distances during WECS failure, processes in emergencies, etc.

Noise. Applicant shall provide an initial sound modeling report and, within six (6) months of commencing operation of the WECS, a postconstruction report for the project with a schedule and documentation …

Setback. The minimum setback from any property line of a Non- Participating Landowner or any road right-of-way shall be no less than 2000 feet. The minimum setback from any property line of a Participating Landowner shall be no less than 1640 feet.

Communication Interference. Each WECS and Testing Facilities shall be designed, constructed and operated so as not to cause radio and television or other communication interference. In the event that verified interference is experienced and confirmed by a licensed engineer, the Applicant must produce confirmation that said interference had been resolved to residents! satisfaction within ninety (90) days of receipt of the complaint. Any such complaints shall follow the process stated in Complaint Resolution sections.

Infrastructure Wiring. All electrical connection systems and lines from the WECS to the electrical grid connection shall be located and maintained underground. …

Road Damage. The Contractor shall inform the Bay County Road Commission (BCRC) of all the roads they propose to use as haul routes to each construction site. This shall be done prior to beginning any construction at any site. The identified haul routes shall be videotaped by either the BCRC or Contractor prior to the beginning of construction and after construction has been completed. Upon review of the before and after videos and physical review of each roadway, the BCRC shall determine what damage, if any, was caused by the Contractor! s vehicles. If it is determined damage to the road was caused by the Contractor! s vehicles or activities, the Contractor shall work with the BCRC to determine the extent of the roadway repair needed. This may include, but is not limited to, crush and shaping the roadway, placing additional aggregate, placing a new chip seal surface (two courses minimum), placing a new asphalt surface or a combination thereof. In all cases, the roadway shall be constructed in accordance with the BCRC! s current specifications and requirements associated with the type of roadway to be installed. All costs for said work shall be the responsibility of the Contractor.

Shadow Flicker. No amount of Shadow Flicker may fall on or in a Non-Participating Parcel. … Participant parcels shall not exceed 30 hours of shadow flicker per
calendar year.

Strobe Effect. No amount of Strobe Effect may fall on or in any parcel. Under no circumstances, shall a WECS or Testing Facility produce strobe effect on properties.

Voltage. The Applicant shall be responsible for compensation to residents for property, including livestock, health or other damage by stray voltage caused by a WECS. The Applicant shall demonstrate WECS prohibits stray voltage, surge voltage, and power from entering ground.

Regulation of WECS Commercial and Industrial Noise. To preserve quality of life, peace, and tranquility, and protect the natural quiet of the environment. This ordinance establishes the acoustic baseline, background sound levels for project design purposes, and limits the maximum noise level emissions for commercial and industrial developments. Residents shall be protected from exposure to noise emitted from commercial and industrial development by regulating said noise.

Non-Compliance with Standards. The Township Board reserves the right to require WECS Applicant to shut down any WECS unit that does not meet ordinance requirements until such WECS unit meets ordinance requirements or is removed.


a) No WECS shall generate or permit to be generated audible noise from commercial or industrial permitted facilities that exceeds 45 dBA (Lmax) or 55 dBC (Lmax) (dBC-to-dBA ratio of 10 dB per ANSI standard S12.9 Part 4 Annex D) for any duration, at a property line or any point within any property.

b) No WECS shall generate or permit to be generated from commercial or industrial permitted facilities any acoustic, vibratory, or barometric oscillations in the frequency range of 0.1 to 1 Hz that is detectable at any time and for any duration by confirmed human sensation or exceeds a sound pressure level from 0.1 to 20 Hz of 50 dB(unweighted) re 20 µPA or exceeds an RMS acceleration level of 50 dB(unweighted) re 1 micro-g by instrumentation at a landowner’s property line or at any point within a landowner’s property.

c) No WECS shall generate or permit to be generated from commercial or industrial permitted facilities any vibration in the low-frequency range of 0.1 to 20 Hz, including the 1, 2, 4, 8, and 16 Hertz octave bands that is perceivable by human sensation or exceeds an rms acceleration level of 50 dB(unweighted) re 1 micro-g at any time and for any duration either due to impulsive or periodic excitation of structure or any other mechanism at a landowner’s property line or at any point within landowner’s property.

d) A noise level measurement made in accordance with methods in section “Noise Measurement and Compliance” that is higher than 45 dBA (Lmax) or 55 dBC (Lmax), adjusted for the penalty assessed for a tonal noise condition, shall constitute prima facie evidence of a nuisance.

e) An acoustic, vibratory or barometric measurement documenting oscillations associated to commercial or industrial permitted facilities with levels exceeding the noise limits shall constitute prima facie evidence of a nuisance.

f) All commercial and industrial activity shall comply with limits and restrictions anywhere at any time on another property.

g) Leq 1-sec shall be used for all measurements and modeling.

Noise Measurement and Compliance. …

Wind Energy Conversion System (WECS) Site Plan Review Procedure. …

Economic Impact. …

—Adopted March 25, 2019

Wind Energy Conversion Systems Zoning Ordinance

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