Auditory grouping is the perceptual process by which the listener separates out the information from an acoustic signal into individual meanigful sounds. A stream is a psychological organisation with perceptual attributes. Important to distinguish physical sources that form acoustic signal from the psychological aspects which create the interpretation. Process of decoding it, perception, is called auditory scene analysis.
Gestalt psychology proposes that the ability to perceive form is inborn.
That there is a propensity to recognise patterns, and relationships between components. Figure and ground. Behavior takes place in an environmental, or psychophysical field in which interacting forces compete until a stable state is reached. Pragnanz, a figure becomes regular, symmetical, simple, stable. Attention can be seen as directing of energy into the grouping processes.