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 systemís 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

Biophony

Dog Barking

Biophony

Northern Cardinal (Cardinalis cardinalis)

Biophony

Red-eyed Vireo (Vireo olivaceus)

Biophony

Lion Roaring

Biophony

Song Sparrow (Melospiza melodia)

Biophony

Biophony

Wood Thrush (Hylocichla mustelina)

Geophony

River Flow

Geophony

Geophony

Diversity of Sound

Waterfall

Spring Peeper

Eastern Wood-pewee (Contopus virens)

Wind Howling

Ecological Analysis of the Soundscape

Purdue UniversityDepartment of Forestry and Natural Resources

Technophony

Cannon Shots

Technophony

Air Raid Siren

Technophony

Technophony

Church Bell

Pneumatic Hammer

Technophony

Jet Fighter Taking Off

Technophony

Traffic Jam

Copyright © 2005, Purdue University, all rights reserved. An equal access/equal opportunity university.† Purdue University, West Lafayette, IN 47907 USA, 765-494-4600

All Spectrograms Generated using:

Raven Lite 1.0. (2005). Cornell Lab of Ornithology, Bioacoustics Research Program.