Auditory Perceptual Organization Research Articles

The Intraparietal Sulcus and Perceptual Organization

The structuring of the sensory scene (perceptual organization) profoundly affects what we perceive, and is of increasing clinical interest. In both vision and audition, many cues have been identified that influence perceptual organization, but only a little is known about its neural basis. Previous studies have suggested that auditory cortex may play a role in auditory perceptual organization (also called auditory stream segregation). However, these studies were limited in that they just examined auditory cortex and that the stimuli they used to generate different organizations had different physical characteristics, which per se may have led to the differences in neural response. In the current study, functional magnetic resonance imaging was used to test for an effect of perceptual organization across the whole brain. To avoid confounding physical changes to the stimuli with differences in perceptual organization, we exploited an ambiguous auditory figure that is sometimes perceived as a single auditory stream and sometimes as two streams. We found that regions in the intraparietal sulcus (IPS ) showed greater activity when 2 streams were perceived rather than 1. The specific involvement of this region in perceptual organization is exciting, as there is a growing literature that suggests a role for the IPS in binding in vision, touch, and cross-modally. This evidence is discussed, and a general role proposed for regions of the IPS in structuring sensory input.

Sensorineural hearing loss and auditory perceptual organization

This talk will consider the implications of sensorineural hearing loss for auditory perceptual organization. In everyday environments, the listener is often faced with the difficulty of processing a target sound that intermingles acoustically with one or more extraneous sounds. Under such circumstances, several auditory processes enable the complex waveforms reaching the two ears to be interpreted in terms of putative auditory objects giving rise to the target and extraneous sounds. Such processes of perceptual organization depend upon the central analysis of cues that allow distributed spectral information to be either linked together or split apart on the basis of details related to such variables as synchrony of onset/modulation, harmonic relation, rhythm, and interaural differences. Efficient perceptual organization must depend not only upon such central auditory analyses but also upon the fidelity with which the peripheral auditory system encodes the spectral and temporal characteristics of sound. We will consider the implications of sensorineural hearing loss for perceptual organization in terms of both peripheral and central auditory processes.

Establishing and maintaining perceptual coherence: unimodal and multimodal evidence

Studies of perceptual organization of speech aim to produce a direct characterization of the fundamental aspect of speech perception by which the listener resolves the acoustically heterogeneous elements of speech into a coherent sensory stream. This primitive function determines a sensory sample fit to analyze for linguistic properties. Organizational functions that apply to speech appear to be fast, unlearned, intended, nonsymbolic and indifferent to the familiar short-term sensory qualities of vocally produced sound. Although primitive auditory organizing principles deriving from the classic Gestalt set fail to accommodate the acoustic variety of speech signals, a claim of specialization in the auditory perceptual organization of speech is not warranted. Multimodal instances of perceptual organization reveal that the detection of coherence across modalities shares formal properties with the detection of coherence within the auditory modality.

Computational audition: Auditory perceptual organization and systematic music theory

The term ‘‘computational audition’’ encompasses top-down and bottom-up approaches in hearing, speech, and music. As an information processing approach, the main task is to relate auditory funtion (i.e.,perceptual processes and representational structures) to structure (i.e., neural circuits). It is argued that there are two main (Gestalt) problems in computational audition: (a) the well-known constancy problems in auditory perception as exemplified in Bekesy (1969, 1974) and (b) the correspondence problem in sequential integration which is the main grouping problem in temporal pattern perception. These problems are best attacked from functional psychophysics and a neuroethological point of view in terms of intercausal nets [Wirkungsgefuege; Mittelstaedt (1969); Bischof (1995)]: Connected functional input–output relations are interpreted as causal relations. Therefore, a research strategy for auditory image formation [Yost (1992)] which may allow connecting signal and information processing approaches is proposed. This functional psychophysical approach to computational audition in connection with neuroethology in research on music perception is called systematic music theory. Computational audition may offer the possibility for a ‘‘theory of music’’ in the sense of Hermann von Helmholtz and Carl Stumpf which is related to a biologically rooted theory of hearing.

Reduced top-down influence in auditory perceptual organization in schizophrenia.

Perceptual organization of auditory information is influenced by both the physical characteristics and the categorization of irrelevant information. This study sought to determine the degree to which schizophrenia patients could utilize acoustic properties and contextual cues (top-down factors) to segregate relevant from irrelevant material in an auditory stream. On a modification of I. Neath, A. M. Surprenant, and R. G. Crowder's (1993) auditory suffix task, both schizophrenia and control participants demonstrated better recall of relevant information when irrelevant information had different physical characteristics, compared with when both arose from the same source. In contrast, schizophrenia patients were unaffected by a contextual manipulation that allowed controls to reduce the interfering effect of an irrelevant stimulus. These data suggest that a reduced ability to utilize contextual information plays a role in the perceptual organization dysfunction in schizophrenia.

Reduced top-down influence in auditory perceptual organization in schizophrenia.

Perceptual organization of auditory information is influenced by both the physical characteristics and the categorization of irrelevant information. This study sought to determine the degree to which schizophrenia patients could utilize acoustic properties and contextual cues (top-down factors) to segregate relevant from irrelevant material in an auditory stream. On a modification of I. Neath, A. M. Surprenant, and R. G. Crowder's (1993) auditory suffix task, both schizophrenia and control participants demonstrated better recall of relevant information when irrelevant information had different physical characteristics, compared with when both arose from the same source. In contrast, schizophrenia patients were unaffected by a contextual manipulation that allowed controls to reduce the interfering effect of an irrelevant stimulus. These data suggest that a reduced ability to utilize contextual information plays a role in the perceptual organization dysfunction in schizophrenia.

On the perceptual organization of speech.

A general account of auditory perceptual organization has developed in the past 2 decades. It relies on primitive devices akin to the Gestalt principles of organization to assign sensory elements to probable groupings and invokes secondary schematic processes to confirm or to repair the possible organization. Although this conceptualization is intended to apply universally, the variety and arrangement of acoustic constituents of speech violate Gestalt principles at numerous junctures, cohering perceptually, nonetheless. The authors report 3 experiments on organization in phonetic perception, using sine wave synthesis to evade the Gestalt rules and the schematic processes alike. These findings falsify a general auditory account, showing that phonetic perceptual organization is achieved by specific sensitivity to the acoustic modulations characteristic of speech signals.