Because the National Park Service works to protect and enhance both park resources and visitor experiences, the Natural Sounds Program differentiates between the physical sound sources and human perceptions of those sounds. The acoustic environment can be defined as combination of all the physical sound resources within a given area. Acoustic resources include both natural sounds (wind, water, wildlife, vegetation) and cultural and historic sounds (battle reenactments, tribal ceremonies, quiet reverence), and a soundscape can be defined as the human perception of those physical sound resources.
The Natural Sounds Program also likes to differentiate between the use of sound and noise, since these definitions have been used inconsistently in the literature. Although noise is sometimes incorrectly used as a synonym for sound, it is in fact sound that is negatively evaluated (undesired) or extraneous to an environment. Humans perceive sound as an auditory sensation created by pressure variations that move through a medium such as water or air and is measured in terms of amplitude and frequency (Harris, 1998; Templeton and Sacre, 1997).

Explore natural sounds at the National Park Service website.