The Perceptual Organization of Streams of Sound

Chapter 3 first explores the principles by which we organize elements of an array into groupings. The Gestalt psychologists proposed a set of grouping principles that have profoundly influenced the study of hearing and vision ever since—these include “proximity,” “similarity,” “good continuation,” “common fate,” and “closure.” Passages of conventional tonal music illustrating these principles are described, along with several illusions and other surprising characteristics of music and speech, all presented as sound examples. They involve the segregation of pitch sequences into separate streams based on proximity in pitch or in time, and also on timbre or sound quality. Figure–ground relationships, analogous to those in vision, are also discussed. Much information arrives at our sense organs in fragmented form, and the perceptual system needs to infer continuities between the fragments, and fill in the gaps appropriately. It is shown that this occurs in both music and speech. We have evolved mechanisms to perform these tasks, but these mechanisms often fool us into “hearing” sounds that are not really there. Another approach to perceptual organization in music exploits the use of orchestral sound textures to create ambiguous images. This approach has been used to excellent effect in 20th-century music such as film scores; for example, it contributes to the mysterious ambience in Stanley Kubrick’s 2001: A Space Odyssey.