AUGUSTA — Maine environmental regulators have given preliminary approval to stricter noise standards on commercial wind farms in a vote that some say marks the first time a board decision has acknowledged that noise issues are a real concern for people living close to large wind turbines.

Petitioners who asked the Board of Environmental Protection to lower the allowable nighttime noise level of the turbines are unhappy that the standards were lowered by only 3 decibels, from 45 to 42, rather than to the 35-decibel level they sought, said Portland attorney Rufus Brown, who represented the petitioners and a group called Friends of Maine’s Mountains. At the same time, they’re glad the board agreed to lower the noise levels and that wind turbine noise was worth addressing.

“So far it’s the only time where the issues we’ve raised have been seriously considered and there’s movement forward,” Brown said. “I think it’s a landmark in that sense.”

In a 5-4 vote Thursday, the board agreed to reduce the allowable noise level of the turbines that can be heard at a home between 7 p.m. and 7 a.m. It also agreed to restrictions over the levels of the rhythmic, pulsating sounds – which have been described as sounding like a pair of sneakers going round in a dryer – emitted by the turbines.

Gordon Smith, a Portland attorney at Verrill Dana law firm, which represents the major wind power developers in Maine, said the science doesn’t fully justify lowering the allowable decibel rate or the board’s decision on pulsating sounds, known as “short duration repetitive sounds,” and how those sounds are measured.

Smith said the new rules could create uncertainty.

“When you’re trying to get developers to work in Maine, changing the regulations and creating circumstances where you don’t really know what the rules are going to be are in and of itself problematic and makes it hard to build projects,” he said.

As wind power projects have spread across Maine, so have the complaints about the noise generated by the turbines.

Residents in Mars Hill, Freedom and Vinalhaven have complained that the noise has caused sleep disturbance, hypertension and other ailments. Brown said some people say the pulsating sound is like someone whispering “hello, hello, hello in your ear all night long.”

Until now, the Department of Environmental Protection has applied a decades-old noise standard to wind energy projects. Critics of large-scale wind projects have said the state needed rules specific to the unique characteristics of wind turbines.

Because the regulatory board’s decision is considered a “major substantive rule,” it must go to the Legislature, which can accept, reject or amend the rule, said DEP spokeswoman Samantha DePoy-Warren. It will likely go to the Legislature in January, after which it will be sent back to the board for final approval.

Brown said he’s concerned lawmakers will undo the board’s actions, particularly given the current anti-regulation political climate.

“Now there’s going to be a whole legislative attack on all this,” Brown said. “The politics are tough and I’m worried that even our modest success may be jeopardized in the Legislature.”

But Smith said wind power companies don’t want to develop projects that cause problems.

“They don’t want angry and unhappy neighbors,” he said. “They want projects that work well and that people will welcome.”