"It's not just noise," Mr. Alexander said. "And I can't get WMATA to give a clear answer on what's going on and what could be causing this to happen. Are the new trains compatible with the tracks? What changed recently?"

Victoria Tyson said she's never noticed the Metro until this summer, when her house started shaking and she noticed problems with her floors. "I had Metro come out with engineers who brought a seismograph," she said. "I finally got a letter in November stating that according to their analysis, the vibrations will not cause damage to my home. They also told me the investigations weren't complete, so how can they know my home isn't or won't be damaged?"

Residents are concerned about any possible changes to the ground, breaking gas or water lines, sinking homes, and as one resident said, "Do I have to worry that my house is going to drop down on me one night?"

Another resident said it wasn't his imagination, "I've never heard this before -- something happened in June."

Doug Arnold, who lives on the 4100 block of New Hampshire Ave, said, "I kept thinking it was a truck passing by or something." But every time he's looked out the window, the street would be empty. "You feel this?" he said to his wife recently while they sat in their living room, "Something is shaking the house."

Ann Chisholm, a WMATA representative at the meeting, said she was there to listen and get feedback, but didn't have any answers to residents' concerns. "We'll take it to a higher power," she replied to one resident who asked what WMATA was doing to address this issue. "We're taking your concerns seriously."

A resident who lives in a basement condo came to the meeting with his neighbor from the second floor, and both said they feel the building shake. "It used to be every 20 minutes, but during rush hour I feel and hear the train every 7 minutes."

Another resident said that he works in his basement and never felt a thing until recently. "My woodshop is in the basement, and I never felt the train. Now, I feel it up on the second floor of my house. It rattles the glasses in my cabinets."