(The Conversation is an independent and nonprofit source of news, analysis and commentary from academic experts.)

(THE CONVERSATION) As transportation networks expand and urban areas grow, noise from sources such as vehicle engines is spreading into remote places. Human-caused noise has consequences for wildlife, entire ecosystems and people. It reduces the ability to hear natural sounds, which can mean the difference between life and death for many animals, and degrade the calming effect that we feel when we spend time in wild places.

Protected areas in the United States, such as national par...