Ecological Strategies and Sonopoietic Space

John Puterbaugh, 1999

Our sonopoietic spaces have evolved through the implicit ecological strategies we have used to survive. Strategies for building sonopoietic images result, in part, from ecological constraints upon the development of our auditory system. An ecological perspective in terms of hearing is that things sound the way they do because of the way we hear and in return we hear the way we do because of the way things sound (See Shepard 1981). Our hearing mechanism evolved in the terrestrial world; not in an aquatic environment, nor in some mediumother than air (See Shepard 1981). Of primary importance to the listener in a terrestrial environment is the spatial location of the sound source and the separation of source into auditory objects, allowing the importance of each source to be individually scrutinized, i.e., we determine where sounds are located and what has produced them. In such an environment, features that provide reliable cues are more ecologically important than those that are unreliable.

Factors contributing to the formation of objects are based on assumptions we have learned to make about sounds in our environment. Bregman (1990) has shown the following properties to be critical in this process of object formation: spatial location (sound perceived as originating from the same place), harmonicity (partials that fall into a pattern as harmonics of a fundamental frequency), proximity in pitch and loudness, similarity between successive events, conformity (to some previously learned sound pattern) and common fate (features shared between elements reflecting their common origins such as onsets, offsets and modulations). If two events exhibit some of these properties, they will fuse into one stream. Otherwise they will be perceived as two separate objects. Most of the time this separation corresponds to the individual sound producing objects in the world, given that our ears evolved in accordance with that world. In the non-terrestrial worlds of synthetic sounds, we begin to hear or reveal discontinuities between our sonopoietic images and the sources of the sound: artifacts caused by our terrestrial ear responding to the periodic drone of synthetic tones, the repetitive oscillation of machinery, the pervading ambience of muzak and elevator music, and the distortion of electric guitars.The permutations and transformations possible within sonopoietic images are related to the physical possibilities in the world. “These rules of transformation are themselves complementary to corresponding regularities governing transformation in the external world” (Shepard 1981). In applying these rules to sounds (whether they have been produced by natural or synthetic means) we define the boundaries of each sonopoietic image.

Shepard, R.H. (1981) Psychophysical complementarity. In Kubovy, M. and Pomerantz, J. (Eds.) Perceptual Organization. Hillsdale: Lawrence Erlbaum Associates.

Bregman, A. (1990) Auditory Scene Analysis: The Perceptual Organization of Sound. MIT Press: Cambridge.