Neuromorphic model for sound source segregation

While humans can easily segregate and track a speaker's voice in a loud noisy environment, most modern speech recognition systems still perform poorly in loud background noise. The computational principles behind auditory source segregation in humans is not yet fully understood. In this dissertation, we develop a computational model for source segregation inspired by auditory processing in the brain. To support the key principles behind the computational model, we conduct a series of electro-encephalography experiments using both simple tone-based stimuli and more natural speech stimulus. Most source segregation algorithms utilize some form of prior information about the target speaker or use more than one simultaneous recording of the noisy speech mixtures. Other methods develop models on the noise characteristics. Source segregation of simultaneous speech mixtures with a single microphone recording and no knowledge of the target speaker is still a challenge. Using the principle of temporal coherence, we develop a novel computational model that exploits the difference in the temporal evolution of features that belong to different sources to perform unsupervised monaural source segregation. While using no prior information about the target speaker, this method can gracefully incorporate knowledge about the target speaker to further enhance the segregation.Through a series of EEG experiments we collect neurological evidence to support the principle behind the model. Aside from its unusual structure and computational innovations, the proposed model provides testable hypotheses of the physiological mechanisms of the remarkable perceptual ability of humans to segregate acoustic sources, and of its psychophysical manifestations in navigating complex sensory environments. Results from EEG experiments provide further insights into the assumptions behind the model and provide motivation for future single unit studies that can provide more direct evidence for the principle of temporal coherence.

White Moths

This collection navigates the process of grief after the speaker’s loss of both parents. The speaker struggles to connect with both the dead and the living through her physical intimacy and relationship with a troubled lover. These poems explore and exhume the speaker’s buried memories, moving from moments of wry humor to meaningful and sometimes painful discovery. Ultimately, these poems attempt to reach beyond the self, to transform loss and loneliness from a human condition into a musical tool of art for human connection.

Not Very Far, But Not Close Either

In “Not Very Far, But Not Close Either”, formal lyrics, free verse poems, and translations from the first century Latin of Martial and Horace explore ideas of distance: the physical distance between bodies, the psychological distance between (and within) human minds, the temporal distance between past, present, and future. A speaker considers his relationship to the image in a foggy bathroom mirror, another to the bird living behind his house, another to the ghosts of his dead parents, whom he asks to watch over a beloved and recently departed child. In exploring these distances—between self and semblance, man and bird, living and dead—the speakers of these poems attempt to locate themselves the only way we can ever locate anything: in relation to something—or someone—else. In this spirit, the manuscript incorporates not only translations and original poems, but poems adapted from and taken after the work of poets who have explored similar themes, questions, and concerns.

Green Circle

The speaker in this collection explores the quotidian experiences of daily life. Often restless, she attempts to find beauty or significance in these occurrences. The speaker looks into her personal history in a variety of locations. Many of the poems are set in Washington DC, California, Massachusetts and South Korea and as such, they explore the intersection of memory and present reality.

Interaction of Acoustic Waves with a Laminar Line-Flame

A systematic study was conducted to elucidate the effects of acoustic perturbations on laminar diffusion line-flames and the conditions required to cause acoustically-driven extinction. Flames were produced from the fuels n-pentane, n-hexane, n-heptane, n-octane, and JP-8, using fuel-laden wicks. The wicks were housed inside of a burner whose geometry produced flames that approximated a two dimensional flame sheet. The acoustics utilized ranged in frequency between 30-50 Hz and acoustic pressures between 5-50 Pa. The unperturbed mass loss rate and flame height of the alkanes were studied, and they were found to scale in a linear manner consistent with Burke-Schumann. The mass loss rate of hexane-fueled flames experiencing acoustic perturbations was then studied. It was found that the strongest influence on the mass loss rate was the magnitude of oscillatory air movement experienced by the flame. Finally, acoustic perturbations were imposed on flames using all fuels to determine acoustic extinction criterion. Using the data collected, a model was developed which characterized the acoustic conditions required to cause flame extinction. The model was based on the ratio of an acoustic Nusselt Number to the Spalding B Number of the fuel, and it was found that at the minimum speaker power required to cause extinction this ratio was a constant. Furthermore, it was found that at conditions where the ratio was below this constant, a flame could still exist; at conditions where the ratio was greater than or equal to this constant, flame extinction always occurred.

My Four Thousand Bibles

This collection exhibits the relationships between generations of mothers and daughters that are often frayed by misgivings about each others’ perspectives and situations. My Four Thousand Bibles is an emotive critique of ideologies that yield these generational problems, while it embraces the fluidity of spirit, being both intimate and echoing. The collection traces an arch of disquietude from a pressurized girlhood, which for the speaker bears the inevitable condition of guilt, unknowingness, and loving faith. Complemented by the records of her grandmother from poor Appalachia and by the challenges of love and partnership, the speaker’s understanding of herself and her position in time develops patience as an observer and participator in the world’s larger turning.