One July afternoon in 1972, a team of psychologists took sound meters into the Bridge Apartments, a cluster of four high-rise buildings straddling Interstate 95 in Manhattan.
Because of the towers’ proximity to the highway, the hum of traffic filled the buildings’ halls. Even on the eighth floor, the decibel level was 66, just slightly quieter than a running vacuum cleaner. The noise died down as the researchers climbed the stairs, though. On the 32nd floor, the reading was 55 decibels, or about the level of a conversation in a restaurant. Decibels are exponential, so this meant the lower floors were about six to 12 times louder than the upper floors, as Colleen Moore, a psychology professor at the University of Wisconsin, explains in her book, Silent Scourge.
The researchers, led by Sheldon Cohen, then with the University of Oregon, discovered something interesting about the children of the families living in that building. School-aged kids living on the lower, noisier floors had more trouble hearing the difference between two similar words, such as thick and sick, than those on the upper, quieter floors.
The children on the noisier floors were also worse at reading. The relationship between the kids’ scores and floor level was strongest for the kids who had lived in the building the longest.