Federal labor officials require workers to wear protective gear and place limits on exposure to noise beginning at 90 decibels. At 100 decibels, the limit is two hours. Precise figures on hearing loss suffered by workers from jackhammers is not available.

The Bloomberg administration made an aggressive overall push to quiet the city, including a new construction code that mandated measures to muffle sound and restricted drilling hours, as well as creating a task force among manufacturers, contractors, utilities and relevant city agencies to devise practical guidelines.

In the months ahead, the city’s Environmental Protection Department will consult with the task force about new regulations the agency is preparing that stipulate “noise mitigation practices and requirements” for jackhammers and “additional technologies for mitigation of jackhammer noise during nighttime construction activities.”

“Builders and contractors are the persons most likely to be affected,” the department notice states, meaning they will have to pay for any new equipment. Most affected, though, will be the beneficiaries: the workers and anyone else within hearing distance.

The existing nighttime noise code, which applies from 6 p.m. to 7 a.m., says jackhammers cannot exceed 95 decibels at about three feet outdoors. The proposed amendment would require sound barriers, muffling blankets or quieter models to make sure that they did not emit more than 85 decibels at 50 feet.

“We do not believe there’s a technological bar to that,” Ms. Preston said.

Most noise emitted by jackhammers is caused by internal parts, rather than by the drill bit striking the pavement. Inside a pneumatic, or air-powered, jackhammer, a piston hits a striker plate as many as 1,800 times a minute. The plate transmits energy to the drill bit, which reverberates — and sounds like a clanging bell.