Made of earthen-color fabric on steel frames up to 32 feet high and 800 feet long, the walls shield industrial machinery from a high school and wetlands greenbelt in Greeley, prairie homes in Windsor, and kids riding bikes and skateboards in Mead. It is the latest innovation for companies equipped with horizontal drilling technology that are trying to solve a puzzle: how to extract more fossil fuels from under where people are living and minimize impact.

The walls help companies meet Colorado's noise limits (55-80 decibels during the day and 50-75 at night, and measured 350 feet from the source). Walls also are being considered for wildlife habitat where proposed drilling threatens mating of sage grouse.

Previously, oil and gas companies tried to ease impact of industrial operations near people by stacking hay bales and shipping containers around engines. Beyond cutting noise by 20 to 30 decibels, the fabric walls partially block the glare of floodlights and dust clouds during companies' multi-month period of drilling and hydraulic fracturing. But industry officials are uncertain whether their voluntary installation of walls will quell the political storm over the oil and gas boom. Rising opposition in Colorado has led to nine statewide ballot initiatives to boost local control and increase required buffers between wells and houses.

The walls are made using 4-inch-thick polyvinyl fixed to steel beams anchored in soil or cement. It takes a few days to build them, depending on length. About $125,000 maintains a wall for two months during drilling and subsequent fracking, the noisiest part of extracting oil and gas. Wind gusts present a challenge, sometimes ripping and fraying the fabric. Encana Oil and Gas has found that noise-related complaints decrease where walls are installed, spokesman Doug Hock said. "It has become the norm in that area (around Mead) and areas where we are drilling in the (Denver-Julesburg Basin) because we are near communities and homes. It makes sense," Hock said. "Given the concerns about noise and dust, it's certainly something we feel we need to do."

Local government leaders confirmed a decrease in noise complaints. Oil and gas companies often conduct noise surveys before and after operations to comply with state limits, which the Colorado Oil and Gas Conservation Commission is charged with enforcing. COGCC officials said they received 17 noise complaints in 2012, 13 in 2013 and 14 so far this year, and they investigate all of them. Anadarko Petroleum Corp. officials are exploring potential benefits of the walls in discussions with residents before drilling begins, stakeholder relations manager Alex Hohmann said.

Noble Energy officials said they've been installing walls around drilling and fracking sites and find them to be effective. The sound-wall company Behrens and Associates Environmental Noise Control, based in Los Angeles, recently bought 5.5 acres east of Longmont at Firestone for offices and a large warehouse, chief executive Don Behrens said. The company is working on about 50 wall projects, including consultations for use of walls to protect the greater sage grouse nesting areas near Hayden on the Western Slope, Behrens said.