The objective of this dissertation research is to identify sounds that grab a listener's attention. These sounds that draw a person's attention are sounds that are considered salient. The focus here will be on investigating the role of saliency in the auditory attentional process. In order to identify these salient sounds, we have developed a computational auditory saliency model inspired by our understanding of the human auditory system and auditory perception. By identifying salient sounds we can obtain a better understanding of how sounds are processed by the auditory system, and in particular, the key features contributing to sound salience. Additionally, studying the salience of different auditory stimuli can lead to improvements in the performance of current computational models in several different areas, by making use of the information obtained about what stands out perceptually to observers in a particular scene. Auditory saliency also helps to rapidly sort the information present in a complex auditory scene. Since our resources are finite, not all information can be processed equally. We must, therefore, be able to quickly determine the importance of different objects in a scene. Additionally, an immediate response or decision may be required. In order to respond, the observer needs to know the key elements of the scene. The issue of saliency is closely related to many different areas, including scene analysis. The thesis provides a comprehensive look at auditory saliency. It explores the advantages and limitations of using auditory saliency models through different experiments and presents a general computational auditory saliency model that can be used for various applications.

Detecting acoustic changes in our environment, such as a rattlesnake’s sudden approach, can be essential for survival. Although auditory change detection has been intensively investigated using sequentially-presented sounds, very little is known about how we detect changes in a natural, complex scene comprised of multiple concurrent sounds. The present study used a location-switch change deafness paradigm; on each trial, participants listened to two consecutive auditory scenes, consisting of three natural sounds played in distinct locations, and reported if the two scenes were the same or identified the two sounds that switched locations. Directing a listener’s attention to a changing sound improved accuracy and decreased reaction time, relative to uncued trials. However, when participants’ attention was invalidly directed to a non-changing sound object, performance suffered. Further analyses showed that these effects could not be explained by energetic masking. Thus, attention is necessary for change identification in complex auditory scenes.

Aging is associated with a decline in the ability to understand what a person is saying in the presence of other sounds. This study investigated the perceptual organization of speech in young (n=20) and older adults (n=20). Four vowels were arranged into six sequences, defined by either continuous or discontinuous first-formant transitions. Participants first made an objective response (choosing the sequence that best matched the one they just heard from a list), followed by a subjective response (indicating if they heard one or two streams of sound). There were significant interactions between age and sequence-type for both objective and subjective responses, respectively. These results suggest that aging affects the ability to perceptually organize speech-sounds and the ability to perceive sequential streaming of speech. These findings are discussed within the context of further enriching what is known about auditory scene analysis, cognitive aging, and sequential streaming.

Detecting acoustic changes in our environment, such as a rattlesnake’s sudden approach, can be essential for survival. Although auditory change detection has been intensively investigated using sequentially-presented sounds, very little is known about how we detect changes in a natural, complex scene comprised of multiple concurrent sounds. The present study used a location-switch change deafness paradigm; on each trial, participants listened to two consecutive auditory scenes, consisting of three natural sounds played in distinct locations, and reported if the two scenes were the same or identified the two sounds that switched locations. Directing a listener’s attention to a changing sound improved accuracy and decreased reaction time, relative to uncued trials. However, when participants’ attention was invalidly directed to a non-changing sound object, performance suffered. Further analyses showed that these effects could not be explained by energetic masking. Thus, attention is necessary for change identification in complex auditory scenes.

Aging is associated with a decline in the ability to understand what a person is saying in the presence of other sounds. This study investigated the perceptual organization of speech in young (n=20) and older adults (n=20). Four vowels were arranged into six sequences, defined by either continuous or discontinuous first-formant transitions. Participants first made an objective response (choosing the sequence that best matched the one they just heard from a list), followed by a subjective response (indicating if they heard one or two streams of sound). There were significant interactions between age and sequence-type for both objective and subjective responses, respectively. These results suggest that aging affects the ability to perceptually organize speech-sounds and the ability to perceive sequential streaming of speech. These findings are discussed within the context of further enriching what is known about auditory scene analysis, cognitive aging, and sequential streaming.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references. Available also from UMI/Dissertation Abstracts International.

Thesis--M. Phil., University of Hong Kong, 1985.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 126-134). Available also in a digital version from Dissertation Abstracts.

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