- website of the Acoustic Ecology Institute
News/IssuesCommunityResourcesSoundscapesAbout UsJoin Us

David Dunn, the tree whisperer? (great bark beetle story, though!)

Arts, Bioacoustics, Human impacts, News, Science, Wildlands Comments Off on David Dunn, the tree whisperer? (great bark beetle story, though!)

David Dunn is a longtime friend and colleague to AEI here in Santa Fe, and in fact his underwater insect recordings were my first taste of the sounds of the natural world having the potential to be deeply strange and amazing, rather than “just” beautiful. So when he discovered that the bark beetles chewing their way through the piñon pines in the hills of New Mexico were making all sorts of bizarre sounds, and suggested publishing a CD to benefit AEI, I was all for it.

Since then, the bark beetle inquiry has taken on a life of its own, becoming a perfect expression of David’s longtime conviction that artists can contribute in significant ways to science.  The acoustic behavior and communication of bark beetles was previously unstudied by entomologists, and now he’s being called to consult with scientists studying not only the piñon pine beetle, but also the mountain pine beetles ravaging larger higher-elevation and higher-latitude pines, as well as insect pests of the non-beetle persuasion.

This past week, a long article appeared in several Canadian newspapers, providing the most detailed look yet at David’s beetle odyssey.  It’s an excerpt from a new book by Andrew Nikiforuk, Empire of the Beetle: How Human Folly and a Tiny Bug Are Killing North America’s Great Forests.  The article dubs David “the tree whisperer,” though so far he hasn’t quite figured out how to calm the outbreaks; in fact, the research so far seems to be leading more toward driving beetles crazy than calming them.  But after forgiving the headline writer, we can sink into he article itself, which is the most detailed, entertaining version yet of David’s beetle adventures.

Ontario wind farm resistance hits court, election

Human impacts, News, Wind turbines Comments Off on Ontario wind farm resistance hits court, election

Ontario is definitely at the heart of current controversies over wind farm siting.  While an environmental tribunal ruled against a health-based appeal in July, allowing the 8-turbine Kent Breeze Wind Farm to continue operating, many of the same issues will soon be argued in court.  A local family that lives just over 1.1km (just under three quarters of a mile) from the nearest Kent Breeze turbine has filed suit against three companies behind the project, saying that since the wind farm went operational in May, they’ve suffered from vertigo, nausea, and sleep disruption, and more to the point, that the developers knew this could happen.

“Within two weeks of them starting up I was in the emergency. I was dizzy and unable to stand. I was given medication and it has been four months and it hasn’t gotten better. I get motion sickness and light headed,” said Lisa Michaud. “At night I’m afraid to lie down because of the constant vibration and spinning.”

At the heart of the court case is the claim that the possibility of health impacts is known to exist, and indeed, parts of the report from the tribunal appeal which lost last month are called on to affirm this:

“This case has successfully shown that the debate should not be simplified to one about whether wind turbines can cause harm to humans,” the Environmental Review Tribunal stated in a report on the Kent Breeze project. “The evidence presented to the tribunal demonstrates they can, if facilities are placed too close to residents.”

In essence the Tribunal ruled that existing Provincial siting rules are sufficient to meet the threshold it imposed; these rules call for at least a 550m setback from homes, about half of what the family filing suit is living with. As reported in detail on AEInews at the time, the Tribunal report is a fascinating overview of the current state of the wind farm noise issue, with long summaries of expert testimony from both sides. The tribunal, while affirming the value of ongoing research into health effects and the nature of wind farm noise, ruled that the more cautionary evidence remained “exploratory,” rather than “conclusive,” and set a threshold for ruling that would require that the wind farm “will” cause “serious harm.”  Short of that, the Tribunal ruled that it could proceed. It seems likely that the court will be asked to review much of the same conflicting testimony; I am not sure whether the legal thresholds are different there than in the Tribunal process.

Meanwhile, the wind boom in Ontario has become a key issue in the current provincial election campaign, with both the candidates taking opposite stands and citizens speaking against current siting standards province-wide. Since the current Liberal government sponsored the Green Energy Act and its current standards, much of the opposition takes a decidedly conservative edge, often including opposition to government support for renewable energy in general and wind energy in particular. It certainly goes far beyond noise concerns for many of the most vocal opponents, with health impacts joining more generally conservative principles in arguments being made. One woman who has had to move from her home recently told a rally that the Liberal government is “denying” the health impacts of turbines and “ignoring” the people who are suffering. “People just aren’t going to sit back and take it anymore…We’re going to have your government so low, so low, so low, you’re not going to get elected. It’s as simple as that.”

Meanwhile, Liberal candidates including current leader Dalton McGuinty note that the standards are among the world’s most precautionary, and refer to a 2010 provincial report that focused on direct health impacts: “I rely on our chief medical officer of health here in Ontario to tell us what’s safe for our families,” McGuinty said Thursday. “What we have heard, of course, is doctors [and] nurses for 20 years now, they’re saying you got to shut down coal-fired generation in Ontario.”

Maine lowers wind farm noise limit to 42dB at night

Human impacts, Wind turbines Comments Off on Maine lowers wind farm noise limit to 42dB at night

The Maine Board of Environmental Protection has approved new wind farm noise standards that will lower night time noise limits to 42dB at the property line of any nearby homesites, a 3dB reduction from the old standard.  The daytime limit of 55dB remains unchanged.  Community groups, which initiated the review with a formal citizens proposal, had encouraged a standard of 35dB. The new rules will need to be approved by the state legislature in January.

Read new rules in full. (note: first half includes markup edits; second half is final version)

The new rules also include detailed procedures for measuring noise and establishing compliance with the noise limits. In the fine print, there is one provision that appears to add noise protection for neighbors, and some that raise questions.  The additional protections include a 5dB penalty if there is moderate blade swich (amplitude modulation) present; any repetitive pulse of sound of 5dB or more will trigger this penalty, meaning the average sound will then need to be 50dB during the day and 37dB at night.

The criteria for establishing compliance raise some questions. Read the rest of this entry »

Victoria 2km wind farm buffer takes effect

Human impacts, News, Wind turbines Comments Off on Victoria 2km wind farm buffer takes effect

The State of Victoria (Australia) has enacted new wind farm siting guidelines that prohibit construction within 2km (1.25 miles) of a home unless the owner has signed off on the nearby turbine(s). In addition, the new guidelines prohibit wind farms within 5km of many existing villages, in order to allow for future growth.  And, several areas with “a high degree of amenity, environmental value, or are a significant tourist destination” are excluded from development. (In Australia and New Zealand, the term “amenity” is often a factor in planning decisions; it largely corresponds to what we might also term rural quality of life.)

The new guidelines set a 40dB noise limit, reduced to 35dB in areas of “high amenity.”  It may be of interest to note that the Victoria planning authorities seem to equate 35dB to about a 2km setback, whereas an Oregon noise standard of 36dB has more often led to roughly half-mile, or 1km, setbacks.  It appears that the noise modeling is using different parameters in Oregon than in Victoria.  It’s also possible that the 2km buffer is designed to protect “visual amenity,” with the noise limit being a secondary feature of the guidelines.

Already, some wind farm developers have cancelled plans to build in Victoria, while locals who have experienced quality of life or health impacts praise the moves. I was especially struck by the reports of Adrian and Helen Lyons, who have 15 turbines within about 3km of their home, with the closest about 1.7km (just over a mile) away; both have reported a feeling of sustained pressure in their ears when the wind comes from the north.  The ear pressure has disturbed their sleep.  This spurs my ongoing question as to whether some of the physical sensations may have more to do with air pressure downwind of turbines, rather than noise levels.  To my knowledge, factors creating pressure differentials have not been investigated, although the related investigation of turbulence effects is on the research agenda of agencies and companies seeking to optimize turbine layout in wind farms.

See this site to download the new Victoria wind planning guidelines.  Or, see this Advisory Note summarizing the new amendments, and this PDF of the full planning and policy guidelines.

Oregon county will not enforce wind farm noise violations

Human impacts, Wind turbines Comments Off on Oregon county will not enforce wind farm noise violations


The Willow Creek Wind Farm has been given a reprieve from needing to address noise violations, as the Morrow County Court (the local name for county commission) decided not to enforce the state noise law.  Oregon has some of the most stringent noise standards, 10dB over night time ambient, which amounts to a noise limit of 36dB; the commissioners decided that the noise violations were minor and rare enough that they would not enforce them, a decision that was largely spurred by the fact that the state has abandoned its noise control enforcement efforts in 1991, leaving enforcement of the state standard to local authorities.

As covered previously on AEInews, dueling sound studies presented very different pictures of the noise violations.  An Invenergy study showed rare violations, but did not study sound at high wind speeds; a sound study by local residents showed excess noise especially at high wind speeds, with one home experiencing noise over 40db on the majority of nights.

“I’m flabbergasted,” said Jim McCandlish, a lawyer for three of the neighbors, after the vote. “The county court has an obligation to protect the health and welfare of its citizens.” McCandlish said his clients’ constitutional right to due process was being denied, and said the neighbors intend to appeal the decision to Oregon Land Use Board of Appeals.

The County’s actions were in part a response to a ruling by LUBA in June that questioned the county’s interpretation of the 36dB noise limit. In its ruling, LUBA sided with the wind developer, which had said that the state laws allow wind farms to produce up to 10dB more than ambient sound levels; the county had been suggesting that if the developer doesn’t conduct ambient noise studies before construction, they must assume ambient of 26dB.  The LUBA decision said that this requirement to choose whether or not to do an ambient study prior to construction did not appear in the state rules, leaving room for companies to show later that measurements of turbine noise levels exceeding 36dB were  made when the ambient was above 26dB.

Wind turbine manufacturers aim to reduce noise

Effects of Noise on Wildlife, Human impacts, News, Wind turbines Comments Off on Wind turbine manufacturers aim to reduce noise

Two recent articles in trade magazines caught me up on efforts taking place within the wind power industry to reduce the noise levels of wind turbines. While it’s great to know it’s on everyone’s mind, it also appears that so far, noise reductions are modest.

In the July 2011 issue of North American Windpower (back issues not available for online reading, sorry to say), one of the feature articles was “Turbine Manufacturers Focus on Reducing Noise Emissions.”  It included discussions with reps from most of the major turbine manufacturers, and was full of fascinating hints of ongoing research.  As the article noted:

As the so-called “low-hanging fruit” of land with good wind and transmission access gets used up and wind turbines move closer to residential areas, noise concerns are expected to become more prevalent, according to wind turbine manufacturers.

“It’s on the top of the minds for all manufacturers,” said Paul Thompson, commercial director of Mitsubishi’s wind turbine group, “we’re all doing things to reduce the amount of noise that’s generated.”  GE’s Henrik Stiesdel stressed that wind turbines do “have a noise impact.  The main remedy is to ensure that they are not sited to close to dwellings. If that’s not possible because you are in a densely populated area, then we have remedies where we control the power output when conditions are such that noise might be exceeding limits.” The article describes this system:

GE’s sound power management (SPM) works by optimizing control setting based on real-time wind conditions, according to Sean Fitzgerald. The SPM option can be configured for day and night modes, at angular intervals depending on the mode switching and based on wind turbine placement. “These applications enable the customer to specify the appropriate, desired sound emission characteristics by customizing the sound power curve to the precise requirements over the entire wind speed range,” Fitzgerald tells NAW.

Gamesa’s Miguel Angel Gonzalez-Posada notes that there’s a trend of having to keep noise as low as possible near populated areas, especially at night.

Read the rest of this entry »

Roanoke County decides 60dB, 1000ft is good for wind farms

Human impacts, News, Wind turbines 2 Comments »

The Roanoke County Board of Supervisors has adopted a wind energy policy that sits on the least-protective edges of current siting standards: a 60dB sound limit, and setbacks of 1000 feet from homes. Four of the five supervisors supported the proposal, saying it would protect residents; the 60dB limit was said to be comparable to sound along US 460, a four-lane federal highway in the area.

A fifth board member, representing the district where the only current wind farm proposal is sited, encouraged the board to hold off on setting absolute limits; Ed Elswick said the county should wait until it has a proposal and hire experts to weigh in “rather than grabbing numbers out of the air.” That didn’t stop him from tossing a number in the hat: he proposed that sound be limited to levels typical of rural areas, suggesting 30dB at the nearest property line.

UPDATE, 10/12/11: Elswick has asked the board to reconsider the 60dB limit; it will be on the agenda at a meeting in late October. Two board members said they knew they wouldn’t change their votes; one said he wanted to hear further discussion, and the fifth board member was not present when Elswick raised the issue again. And, 26 local residents have sued the Board of Supervisors, saying that the sudden shift from a 2600-foot setback proposal to the 1000-foot decision lacked proper notice of a public hearing, and was “clearly unreasonable, arbitrary or capricious.” UPDATE, 10/26/11: The Board of Supervisors voted to not reconsider their previous decision.


The area where 15-18 turbines are currently proposed is a section of hills about ten miles from Roanoke, a near-to-town rural enclave that has federal highways two to four miles in two directions, along with I-81 a few miles distant (see 2 mile scale at lower left, above). It appears that no existing ambient levels have been determined there, though it would not be surprising if some of the highways are faintly audible at the site.  There may well be homes in valleys, however, where current soundscape conditions are notably free of road noise, and which will now face next-to-the-highway noise levels from turbines on ridges nearby.

It is unclear at this point how many homes are close to the 1000-foot setback distance; these will be the places where the soundscape is likely to be most dramatically changed. A half-mile setback was proposed in a previous draft of the policy; this would have likely minimized the likelihood of major impacts on neighbors, though it may not have eliminated noise issues entirely. In areas such as this, it’s often hard to site wind farms without fairly relaxed noise and setback limits.  Here, as in many other towns and counties, board members apparently felt that it was more important to not exclude wind development than it was to maintain current soundscape conditions in this rural enclave.

NY windfarm latest to trigger noise issues – it’s easy to see why

Human impacts, News, Wind turbines Comments Off on NY windfarm latest to trigger noise issues – it’s easy to see why

A sprawling wind farm in northern New York state is the latest new installation to trigger push-back from neighbors complaining about excessive noise.  The Hardscrabble Wind Project is centered in Fairfield, just north of I-90 between Syracuse and Albany; its three-dozen turbines stretch across parts of three towns, covering an area of roughly ten miles by three miles.

Hardscrabble herkimer fairfield NY

A recent local press report summarizes the current situation: several nearby residents have complained of noise issues, leading the developer, Iberdrola, and the town of Fairfield to commission noise studies to determine what sound levels were occurring.  The Iberdrola study found that sound was generally in line with the predictions made during project planning, falling below the regulatory limit of 50dB, though in high winds some recordings came in above that with combined turbine and ambient wind noise.  The town study will take place this winter, when the leaves are off the trees.

UPDATE, 10/4/11: Good local article on the preparations for the new noise study, with a classic example of neighbors reacting differently to the sound, one saying the noise “is really bad, very hard to live with,” and another saying “to be honest with you, I don’t even notice them.”

A look at the sound assessment documents compiled as the project was being approved offers some hints as to why this project might trigger noise complaints; several factors compound the likelihood of issues here.  First is the town’s noise limit of 50dB for non-participating neighbors, which is on the very high end of regulatory limits for wind farms.  The sound assessment went through several versions as the project was revised and refined; a noise analysis from March 2009 lists 25 homes where the modeled noise levels were predicted to be between 45 and 50dB; 11 were hosting turbines and 14 were not. An apparently final revised noise analysis dated December 2009 (after some site adjustments to some turbines) does not list the affected homes, but includes very detailed sound contour maps, which show well over a hundred homes sitting in the 40-50dB zone, where it can be expected that a significant minority of residents will find the noise intrusive (based on experience at other wind farms in similar communities, and on the limited research data we have available; for more on this, see AEI’s 2010 NEWEEP presentation on community responses).  It all adds up to the classic conditions that have often led to problems in rural towns that are home to many residents who are not actively farming and ranching: too many homes receiving noise levels close to (relatively high) regulatory limits.

The final hint that there might be problems lies in the March noise assessments definition of existing ambient noise. This is often the key factor that is given too little attention in wind farm siting,

Read the rest of this entry »

In-depth soundscape ecology study underway at Alaskan wildlife refuge

Effects of Noise on Wildlife, News, Science, Vehicles, Wildlands Comments Off on In-depth soundscape ecology study underway at Alaskan wildlife refuge

A really fascinating multi-year study is underway at the Kenai National Wildlife Refuge which sits on a peninsula along the south side of the Cook Inlet in Alaska (Anchorage and Wasilla are at the innermost tip of Cook Inlet).  Tim Mullet, a Ph.D. student at what looks like an amazing program at the Institute of Arctic Biology, is undertaking what may well be the most comprehensive soundscape analysis ever undertaken on a landscape scale. “As far as I know, nobody has attempted to model sound in the landscape,” says Mullet. “We could encounter some big surprises there.”

Over several summers and winters, he is collecting recordings with 13 units placed in different areas of the refuge; some are permanent locations, and others he moves around in order to explore the soundscape in more areas. He already has 85,000 hours of sound data, and hopes to expand his recorder array to 23 units this year as well. These two articles provide a great overview of what Tim’s up to.

Snowmobile density in the Kenai NWR (red most, blue least); note that the shaded areas on the east side are nominally closed to snowmobile traffic, yet show some sign of activity.

Snowmobile density in the Kenai NWR (red most, blue least); note that the shaded areas on the east side are nominally closed to snowmobile traffic, yet show some sign of activity.

“At this point, I’ve got an idea that 30 to 40 percent of Kenai’s wilderness could be affected by human–made noise,” says Mullet. The study goes beyond simple decibels (loudness), though. It is a foray into the emergent field of soundscape ecology, which examines the interplay of anthrophony (human–induced sounds) and biophony (natural sounds).

Loudness is “a piece of this study,” says Morton, “but another piece is the origin of sound—whether it’s human or nature—and developing a ratio between the two. It’s definitely cutting edge.” Understanding the relationship between anthrophony and biophony is important to the refuge and wildlife conservation in general, Morton says, because “human–generated noise can drown out natural noises—and that can be a huge deal, to the point where animals can’t actually hear themselves.”

In addition to collecting and mapping sounds, Mullet is studying whether moose who live closer to high levels of sound show higher stress levels than those in more sonically pristine areas.  While some snowmobiling advocates seem concerned that Mullet’s work may lead to new restrictions on their access to the refuge, Mullet himself understands and appreciates the key role of snowmobiles in Alaskan recreation, and aims to simply clarify what the various cumulative impacts of noise may be. Snowmobile trails create other impacts as well, especially compacting snow, which can benefit wildlife by offering travel paths, though biologists are also interested in how this easier travel may shift some predator/prey relationships.

More info: See two articles written by Mullet, one on the many qualities of snow, and the other exploring our different ways of listening, and introducing the Kenai study.  Also of interest from Tim is this research proposal, which summarizes previous research into both the impacts of noise and other snowmobile impacts (unfortunately, the sections of the proposal that are yellow-highlighted come through on the pdf as blocked out).

Magical more efficient wind turbine of the month

News, Science, Wind turbines Comments Off on Magical more efficient wind turbine of the month

Wind 200

A Japanese research effort that’s been around for a while has gotten a blast of media fame this week, claiming the potential to triple power generation by using a ring around the blade-swept disc that focuses wind past the blades, as well as, I think, capturing some of the energy off the blade tips.  Sounds great in a headline, but as with most new turbine design “breakthroughs,” this one is early in R&D: the field trial models are only 5kw, with two 100kw, 13m-diameter, models recently erected. Whether the design can scale up, or be constructed economically in large arrays of smaller units, remains to be seen.  The weight of the ring has to be a challenging design feature when it comes to actually building large versions of this in the real world. Nearly every efficiency-improvement approach also touts a reduction in noise output as one of the benefits.

The best coverage of the “Wind Lens” research appeared on Clean Technica; they included these links to the lab’s research page and a conference poster. For good measure, here’s a couple other new approaches to increasing turbine efficiency previously covered in Clean Technica, with equally uncertain futures.  More power to all these researchers, whether in university labs or backyards.  Just don’t assume that a catchy headline means the revolution is neigh.  (Being a dreamer, I remain quite fond of ongoing research in California that seeks to harness extra energy by mimicking fish schooling patterns with small vertical-axis turbines, as covered previously here.)