Natural and urban noise has a broad, smooth power spectrum.

Evidence

Noise is a common companion out-of-doors. The rustle of leaves, the sound of a waterfall, waves on a beach, feet shuffling along the ground are all noise sources. We now have many additional sources of outdoor noise, such as jet aircraft, cars passing by, and the general din of cities. The power spectrum of such noise is often not gathered into many sharp peaks, but rather diffused over very broad frequency ranges. If an average is taken over a long time, the power spectrum is a smooth continuum. — Eric J. Heller, Why You Hear What You Hear- An…, 2136

Categorization

• XREF: Pairs with prior soundscape/noise material on lo-fi environments and their structure.