Scientists at the National Park Service released a map earlier this week showing the noise levels in the country. The map reveals that the quietest places in the United States can be found west while the loudest are on the east.

Kurt Fristrup, study leader and a bioacoustics researcher, worked with his colleagues in collecting 1.5 million hours of recordings from 600 sites across the country for 10 years during the summer. They ranked the loudness of the sites from 0 to 67 decibels using computer algorithms.

It is a fact that big cities are louder than the rural areas, but the researchers were surprised that the noise exists even in remote areas such as Denali, Alaska, according to Popular Science.

"I was surprised by the ubiquity of aircraft noise across all parks," Fristrup said at the presentation.

The noise analysis showed that the quietest places in the United States, which are below 20 decibels of background noise, are in the Yellowstone National Park in Wyoming and the Great Sand Dunes National Park in Colorado. Los Angeles, New York City, and Dallas, on the other hand, are the loudest places in the country with noise levels of at least 50 decibels.

Fristup warned that the increasing levels of background noise threaten to make people unaware of the sounds of nature such as the birdsong, running water, and trees swaying in the winds. These natural noise are detected even in the cities, but since people are always using their earphones, they are not hearing them anymore, The Guardian reported.

"This learned deafness is a real issue," Fristrup said. "We are conditioning ourselves to ignore the information coming into our ears."

"There is a real danger, both of loss of auditory acuity, where we are exposed to noise for so long that we stop listening, but also a loss of listening habits, where we lose the ability to engage with the environment the way we were built to," he added.

The researchers plan to continue their study to determine if the background noise are driving the wildlife away. But the sound map can also be useful to urban planners and biologists who are seeking to preserve the "natural quiet."

The map was presented at the annual meeting of the American Association for the Advancement of Science.