This thesis presents the design and implementation of a generative model of tonal tension. It further describes the application of the generative model in realtime sonification. The thesis discusses related theoretical work in musical fields including generative system design, sonification, and perception and cognition. It highlights a review of the related research from historical to contemporary work. It contextualizes this work in informing the design and application of the generative model of tonal tension. The thesis concludes by presenting a formal evaluation of the system. The evaluation consists of two independent subject-response studies assessing the effectiveness of the generative system to create tonal tension and map it to visual parameters in sonification.

Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Cunefare, Kenneth A.; Committee Member: Qu, Jianmin; Committee Member: Ryherd, Erica. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 52-56).

In animal communication, individuals within a species often vary widely in their behavioral responses to species-typical signals. These variations in behavior may be due to differences in the sensory processing of communication signals. Sensory processing of behaviorally relevant stimuli is likely to be influenced by reproductive hormones. Here I report investigations on the influence of sex and reproductive condition on auditory processing in the green treefrog, Hyla cinerea. I conducted electrophysiological experiments that tested how sex and reproductive condition influence the neural representation of sounds in the auditory midbrain, the torus semicircularis. I found differences between and within the sexes that were both frequency-dependent (low vs. high frequency) and stimulus-dependent (tones vs. calls). For sex differences at auditory threshold, females were less sensitive to frequencies outside the spectral range of the male advertisement call and were not different from males inside the range. Sex differences were also stimulus-dependent with females more sensitive to the advertisement call than males. For stimuli consistent with close-range communication, I tested whether or not sex differences in response strengths to advertisement call and noise stimuli depended on the reproductive state of the female. I found that in response to low frequency stimuli postmated females had significantly reduced response strengths compared to males and unmated females. Additionally, I tested whether circulating reproductive hormones influenced auditory processing by manipulating androgen levels and assessing neural thresholds and response strengths to auditory stimuli. Elevated androgen levels in females resulted in increased thresholds and reduced response strengths but only in response to stimuli that are consistent with species-typical communication. Together the evidence from these studies suggest that sex and reproductive hormones influence auditory processing in a way that shapes the filtering properties of the auditory system for the detection of communication signals.

Crickets provide a useful model system to study how animals analyze sound frequency. While much is known about how sound frequency is represented by central neurons and in behavior, little is yet known about auditory receptor neurons. I investigated physiological and anatomical properties of auditory receptor fibers (ARFs) and functional organization of their axon terminals, using single-unit recording and staining techniques. Behavioral experiments suggest that crickets are sensitive to two broad frequency ranges, centered at 4--5 kHz for acoustic communication and at 25--50 kHz for predator detection. However, cricket ARFs fall into three distinct populations, based on characteristic frequency (CF; low frequency, ∼3--5.5 kHz; mid frequency, 9--12 kHz; ultrasound, ≥18 kHz). One striking characteristic of single ARFs is the occurrence of multiple sensitivity peaks at different frequencies, which implies that the wide audible range of crickets is mediated by these multiple sensitivity peaks, even though CFs of ARFs are clustered at the three small ranges. To understand how populations of ARFs code sound intensity, level-response functions are examined. Physiological parameters derived from level-response functions are diverse, and are systematically related to threshold within each population. Low-frequency ARFs comprise two distinct anatomical types, based on the distributions of axon terminals, which also differ physiologically. Thus, based on CF and anatomy, cricket ARFs can be classified into four distinct populations. To understand how information flows from peripheral to central neurons, the positions of varicosities, i.e. output sites, of ARF axon terminals are mapped on a two-dimensional coordinate system. In crickets, the ARF axon terminals are functionally organized with respect to frequency and intensity. Anatomical organization with respect to threshold is related to physiological organization, which may reduce non-linear effects in postsynaptic

This thesis used the electroencephalogram (EEG) to measure the electrophysiological correlates of auditory distraction. Chapter One determined that relative to broad-band noise, the presence of a continuous speech signal impaired task performance, attenuated the N1 peak and reduced theta/alpha band inter-trial phase coherence around the latency of the N1. Chapter Two found that reductions of inter-trial phase coherence during distraction were related to both disruptions of gain and the temporal fidelity of evoked responses. Chapter Three found that postsecondary adults with ADHD are not characterized by greater levels of distraction and that this population may be responding to sensory events with abnormally high phase locking. Chapter Three also found that Un-medicated ADHD adults had significantly more N1 latency, theta/alpha band evoked power than Medicated ADHD or Control groups. These results extend the literature on distraction by using time-frequency measures to assess how distraction modulates early sensory processing of stimulus events. / xxii, 171 p. : col. ill. ; 29 cm

We have designed a system suitable for auditory electroencephalographic (EEG) experiments, with the objective of enabling studies of auditory motion. This thesis details the perceptual cues involved in spatial auditory experiments, and compares a number of spatial panning algorithms while examining their suitability to this purpose. A behavioural experiment involving perception of static auditory objects was used in an attempt to differentiate these panning algorithms. This study was used to inform the panner choice used in an auditory EEG experiment. This auditory EEG experiment involved the effects of discontinuity in velocity and position, and their affects on object perception. A new event related potential (ERP) component – the lateralized object related negativity (LORN) – was identified, and we consider its significance. libnetstation, a library for connecting with the NetStation (EEG) system has been developed, and released as open source software. / viii, 61 leaves : ill. ; 29 cm

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Modelling a listener's perception of musical rhythm requires both an understanding of rhythm as a whole as well as a definition of its constituent elements. The hypothesis is that once we can adequately define rhythm, we can then begin to design and implement models to gain insight into the perceptual processes which occur when listening to rhythmic sequences. This research outlines studies which have attempted to define and outline both the structure and the perception of rhythm. Based on the conclusions of these investigations, a computer model is designed and implemented using connectionist techniques. The emphases on this model are to arrive at a viable solution for extracting rhythmic material from performed input, and to implement time-scale invariance. Time-scale invariance allows the system to recognize (categorize) similar patterns played at different tempos as being the same pattern. The performance of this model is evaluated against earlier models designed with similar neural network architectures as well as in relation to the conclusions drawn by music theorists and psychologists.