Deep blue regions, such as Yellowstone National Park in Wyoming and the Great Sand Dunes National Park in Colorado, have background noise levels lower than 20 decibels — a silence likely as deep as before European colonization, researchers say. (sciencemag.org)
The high - grade silicone earplugs will stay securely in place thanks to the well - designed triple flanges, and will reduce background noise levels without muffling. (geekwrapped.com)
Last year, researchers found that great tits (Parus major) spontaneously change their tune depending on background noise levels. (newscientist.com)