1993 — 1997 |
Shofner, William P |
P01Activity Code Description: For the support of a broadly based, multidisciplinary, often long-term research program which has a specific major objective or a basic theme. A program project generally involves the organized efforts of relatively large groups, members of which are conducting research projects designed to elucidate the various aspects or components of this objective. Each research project is usually under the leadership of an established investigator. The grant can provide support for certain basic resources used by these groups in the program, including clinical components, the sharing of which facilitates the total research effort. A program project is directed toward a range of problems having a central research focus, in contrast to the usually narrower thrust of the traditional research project. Each project supported through this mechanism should contribute or be directly related to the common theme of the total research effort. These scientifically meritorious projects should demonstrate an essential element of unity and interdependence, i.e., a system of research activities and projects directed toward a well-defined research program goal. |
Processing Harmonicity and Intensity of Complex Auditory Signals @ Loyola University of Chicago
The formation of auditory images from complex sound sources is an important function of the human auditory system. Several physical characteristics of complex sounds have been described to be important for the formation of auditory images. In this project, we describe experiments directed at gaining an understanding of the role of harmonicity and intensity in auditory image formation. Intensity can refer to the overall sound level of a stimulus or it may refer to the intensity profile of a stimulus. Harmonicity is closely related to the perception of pitch which is an important perception of many complex sounds, including speech and music. We will specifically focus on the auditory processing of stimulus features related to harmonicity and intensity of different types of noise signals, particularly rippled noises and bandlimited noises. Rippled noises produce the perception of pitch in humans and can be broadband or bandlimited signals. The proposed experiments involve human psychophysics and computer simulations, animal behavior, and single neuron recording. In human psychophysical experiments, we will continue to define the sensory and perceptual capabilities of the auditory system for processing spectrally rippled stimuli, including iterated-rippled noises and log-rippled stimuli. These studies will also include simulations using the Pulse- Ribbon Model of Roy Patterson. In animal experiments, we will study rippled noise processing in the chinchilla using positive reinforcement, psychophysical procedures which will allow us to define the sensory capabilities of this animal for processing rippled noise stimuli. As part of this effort, we will also study the ability of the chinchilla to detect intensity increments of bandlimited noise. Finally, we will study the neural representations of the temporal and spectral characteristics of rippled noises and bandlimited noises in the discharge patterns of neurons in the chinchilla cochlear nucleus. These studies will allow us to compare the results from the chinchilla psychophysical experiments to neuronal responses in the chinchilla cochlear nucleus and to human psychophysical data. These experiments will provide important insights into the neural processing of harmonicity and intensity of complex sounds in humans.
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0.933 |
1998 — 2002 |
Shofner, William P |
P01Activity Code Description: For the support of a broadly based, multidisciplinary, often long-term research program which has a specific major objective or a basic theme. A program project generally involves the organized efforts of relatively large groups, members of which are conducting research projects designed to elucidate the various aspects or components of this objective. Each research project is usually under the leadership of an established investigator. The grant can provide support for certain basic resources used by these groups in the program, including clinical components, the sharing of which facilitates the total research effort. A program project is directed toward a range of problems having a central research focus, in contrast to the usually narrower thrust of the traditional research project. Each project supported through this mechanism should contribute or be directly related to the common theme of the total research effort. These scientifically meritorious projects should demonstrate an essential element of unity and interdependence, i.e., a system of research activities and projects directed toward a well-defined research program goal. |
Role of Temporal Processing of Harmonicity in Source Determination @ Loyola University of Chicago
Harmonicity and its resulting temporal regularity are cues that might be used for sound source determination. Such complex stimuli often generate the perception of pitch. This project addresses issues concerned with temporal processing of the pitch of complex sounds, primarily rippled noises. Rippled noise generates complex pitch perceptions, exactly like those produced by many other complex stimuli. Complex pitch is one possible cue for sound source determination. Previous human psychophysical work suggests that the processing of iterated rippled noise can best be explained by temporal mechanisms such as might be revealed by forms of auto-correlation. Thus, a major focus of this project is on temporal processes such as auto-correlation. This project uses a multi-disciplinary approach based on human psychophysics, animal psychophysics, animal neurophysiology, and modeling to gain insights into the temporal mechanisms underlying pitch perception. A series of human psychosocial experiments is designed to determine how well auto-correlation and its neural analog, summary correlograms, can account for the pitch and pitch strength of complex sounds such as iterated rippled noise. In the animal psychophysical experiments, the perceptual capabilities of the chinchilla for processing the same types of rippled noise stimuli used in human psychosocial experiments will be evaluated. One goal is to determine if the mechanisms responsible for the perception of complex pitch in human subjects are unique or special to the human nervous system or whether these are common neural mechanisms that exist across mammals. In neurophysiological experiments, the neural representations of the temporal and spectral characteristics of the same rippled noises used in the human and chinchilla psychophysical experiments will be explored. Most of the physiological work will involve studies of single neurons in the chinchilla cochlear nucleus. The goal is to understand how information about harmonicity and its resulting temporal regularity and pitch are represented and processed in the auditory system.
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0.933 |
2004 — 2008 |
Shofner, William P |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Periodicity Processing in the Auditory System @ Loyola University of Chicago
DESCRIPTION (provided by applicant): Many different complex sounds, including speech and music, have acoustic waveforms that possess some form of temporal periodicity, and pitch is a fundamental human perception closely related to this temporal periodicity. We propose to address issues concerned with the temporal processing of complex sounds, primarily complex tones and iterated rippled noises, as related to pitch perception. A variety of attributes are associated with the perception of pitch, and we propose to address issues concerned with four specific perceptual attributes, namely, matched pitch, spectral dominance, pitch strength and phase effects. The major goal is to understand the neural basis of pitch perception in humans. We propose to use a multidisciplinary approach based on animal psychophysics and neurophysiology in order to gain insights into the temporal mechanisms underlying pitch perception. In animal psychophysical experiments, the perceptual capabilities of the chinchilla for processing the same types of complex sounds used in human psychophysical experiments will be evaluated. The goal of these behavioral experiments is to determine if the underlying neural mechanisms responsible for the perception of complex pitch in human subjects are unique or special to the human nervous system, or whether these are common neural mechanisms that exist across mammals. In physiological experiments, the neural representations of the temporal features of the same complex sounds used in the human and chinchilla behavioral experiments will be studied at the first level of auditory processing, namely, the cochlear nucleus. The goal of the physiological experiments is to understand how information about waveform and envelope periodicities is represented and processed in each of the various principal subsystems in the cochlear nucleus. The comparisons between neurophysiological data and behavioral data from the chinchilla with human psychophysical and perceptual data will provide an important biological context in which to understand the basis of human pitch perception.
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