“It was so loud I could not hear myself think,” said Elena Ruehr, a composer who splits her time between Brookline and Wellfleet. “I felt like there was a giant mosquito hovering over me.”

Last week, residents of Wellfleet, Eastham, and Orleans had similar complaints. The reason for the noise, it turns out, was Eversource installing optical ground wire, or OPGW, on their transmission structures via helicopter.

It started on Nov. 9, but will, weather permitting, be finished by this weekend, said Eversource spokesperson Priscilla Ress. They carry out the work from 7 a.m. to 4 p.m.

According to Ress, OPGW “protects important equipment from lightning with the added benefit of containing optical fibers to transmit data.” She said OPGW will also reduce the duration of power outages.

“Over the years, Eversource has learned that the fastest and most efficient way to install the transmission wire in areas like Cape Cod is by using a helicopter,” said Ress. This way the work requires less equipment and fewer vehicles on the ground. The company says the approach results in “fewer impacts to residents and environmentally sensitive areas.”