Diversity of Sound

Sound Is...

As with most realms of scientific inquiry, categorization and characterization of the information is needed to facilitate our understanding of the acoustic elements of ecosystems. Therefore, a system of signal classification that relates signals to their sources and intents was developed by Dr. Stuart Gage of Michigan State University and others. This classification system focuses on the two primary acoustic contributions to the soundscape, biological and geophysical sounds. Geophysical signals are the sounds generated by geophysical (i.e. inorganic) activity in the earth system. This includes wind, rainfall, thunder, water flow noises, earthquakes and volcanoes, and is referred to as the geophony.

The other component of the soundscape, the biophony, consists of signals with more temporal and spectral variability. This class encompasses the array of sounds generated by the earth system’s living entities. These include birds, amphibians, insects and mammals. As a biological component of the earth system, human vocalizations technically fall within the realm of biophony. As a species, however, we are responsible for another set of signals outside the realm of organic vocalizations. These signals result from our use of extrasomatic energy to accomplish various ends via technological innovations. The term technophony refers to this class of signals that comprise an offshoot of the biophony.

The examples below represent some of the diversity of sounds in these categories. Click on any of the spectrograms to enlarge them and hear the sound.

Biophony

Californius myotis (Bat) Using Echolocation

Biophony